Time and/or Temperature Sensitive Devices and Methods of Use Thereof

ABSTRACT

An apparatus, system and method for a time temperature indicator (TTI) which is capable of providing a summary of the time and temperature history of a good to which it is coupled, optionally including with regard to providing an indication as to whether one or more temperature thresholds have been breached. According to other embodiments, the TTI specifically provides an indication as to whether a temperature threshold at or around the freeze point has been breached, optionally even without providing a time and temperature history.

FIELD OF THE INVENTION

The present invention, in some embodiments thereof, relates totemperature sensitive applied materials and devices, and, moreparticularly, but not exclusively, to temperature indicators, whether asa threshold, a temperature history or a combination thereof, optionallywith a visually and/or instrumentally visible summary of the elapsedtime-temperature profile the device had experienced, for variousbusiness applications.

BACKGROUND OF THE INVENTION

Time temperature indicators (alternatively called “time temperatureintegrators”) are devices that are characterized by at least onechangeable observable physical property that progresses at a rate thatis proportional to the temperature or at a rate that is proportional tothe temperature and the time, and thus provide an indication of the fullor partial time-temperature history of their immediate surroundings.Time temperature indicators (TTIs) are simple and inexpensive devices,typically designed as labels. When attached to a perishable good, a TTI(appropriately designed and calibrated) monitors its time-temperaturehistory and provides a simple, usually visual, straightforward summaryof the exposure history of the product to time-temperature, therebyproviding indication of the product's freshness condition. Consequently,TTIs are among the most promising shelf-life-report technologies.

The TTI concept was developed to ensure the safety and quality ofperishable goods, such as food and drug products, throughout theirentire lifespan, from manufacturing to the time they are consumed by theend-user. The safety and quality of many perishable goods such as food,drugs, vaccines and blood, depend mainly on appropriate storageconditions during distribution and storage. Different factors such asgas composition, relative humidity and temperature affect their reallifetime. The fact that changing conditions affect the effectiveshelf-life of these kinds of goods is not reflected by a “best before .. . ” type label that relies on appropriate storage conditions. Of allstorage factors, temperature abuse is the most frequently observedfactor for deterioration, based on diverse physical, chemical, enzymaticor microbial processes. Therefore, the TTI technology can provide asimple tool for controlling the food and drug supply-chain. The colorand/or other visual physical properties of the TTI varies as a functionof the time at a rate which is temperature dependent or time-temperaturedependent, thus providing an active scale of “freshness” of the productto which it is attached, by comparing the color (or darkness) or anyother varying visual property of the TTI label with a given comparativescale. Since the TTI indicators may be designed to provide a distinct“Yes” or “No” type of answer regarding the time temperature factor, theymay provide an important “clear cut” answer and save further elaboratedata inspection. This is ideal for HACCP (Hazard Analysis CriticalControl Point), where the emphasis is on real time decision making andaction.

Various TTIs are disclosed, for example in the following patentpublications. U.S. Pat. No. 4,737,463 discloses a photoactivatabletime-temperature indicator based on diacetylenic salts. A thermallyunreactive (“inactive”) diacetylenic salt (or a mixture of such salts)is mixed, in a polymeric matrix, with a material that generates acidupon exposure to light. Photoexcitation, preferably by UV or near UVlight, causes the formation of a thermal reactive (“active”) freediacetylenic acid. Following this activation step, a progressive colordevelopment occurs at a rate that increases with temperature. Theindicator is useful for monitoring the freshness of perishable products,particularly those that require refrigeration.

WO 99/39197 discloses a technique, which provides a substrate forpackaging time- and temperature-sensitive products or for applicationthereon. According to this technique, planar time-temperature integratoris used consisting of a matrix and at least one reversible indicatorembedded therein being arranged in the area of the substrate. Theindicator has photochromic properties.

U.S. Pat. No. 6,435,128 discloses a time-temperature integratingindicator device that provides a visually observable indication of thecumulative thermal exposure of an object. The device includes asubstrate having a diffusely light-reflective porous matrix and abacking. The backing includes on its surface a viscoelastic indicatormaterial for contacting the substrate and a barrier material forsubstantially inhibiting the lateral and longitudinal flow ofviscoelastic indicator material between the substrate and the backing.

U.S. Pat. No. 6,042,264 discloses a time-temperature indicator device,designed as a label, for measuring the length of time to which a producthas been exposed to a temperature above a pre-determined temperature.The period of time of exposure is integrated with the temperature towhich the indicator is exposed. The label is a composite of a pluralityof layers adapted to be adhered at its underside to a product container.The label includes a printable surface layer, a longitudinal wickingstrip that is adhered underneath the surface layer substantially at theopposite extremities only of the wicking strip and a lower substratelayer forming an envelope with the surface layer. A heat-fusiblesubstance, which melts and flows above a pre-determined temperature, isapplied on the surface of the wicking strip contiguous to at least oneof the ends of the wicking member. When the heat-fusible substance isexposed to a temperature above the pre-determined temperature, theheat-fusible substance flows along the length of the wicking member. Thelabel has a printable surface layer and is sealed at its peripheral edgeto the peripheral edge of the substrate layer. These layers encapsulatethe wicking member and the heat-fusible substance. The surface layer isprovided with a sight window at an intermediate location over thewicking member through which the progress of flow on the wicking memberis observed.

PCT Publication Application No. WO 03/077227 discloses a time indicatinglabel comprising a label substrate having first and second surfaces, anacid-based indicator composition, and an activator composition. One ofthe acid-based indicator composition and the activator composition is onthe first surface of the substrate, and both of these compositions whenbrought in contact remain adhered. The label may have a pressuresensitive adhesive on the second surface of the label. The labelprovides an effective means for determining the safety of frozen foods.The labels also provide a means of providing security by providing namebadges that are time sensitive and may not be reused. The name badgesprovide a means to monitor the length of a visitor's time and preventreusing the name badge.

PCT Publication Application No. WO 03/044521 discloses a sensor adaptedto be remotely readable by RF techniques for identification of thequality of a packaged foodstuff. The sensor either reacts with compoundsgenerated in the atmosphere of the foodstuff package due to themicrobiological decay of the foodstuff, for example hydrogen sulfide orother sulfide compounds, or the sensor is responsive to an increasedoxygen content in the atmosphere of the package due to a leakage in thepackage. The sensor is based on a RF circuit. Oxygen or themicrobiologically generated gas affects the electrical properties of thecircuit material. For example, the resistor, the capacitor or theinductive coil of the circuit or at least a fraction thereof are made ofsilver, iron, aluminum, a redox-type indicator-dye, a conductivepolymer, or copper. Due to the reaction of the aforementioned gases withthese materials, the sensor resistance, conductivity, capacitance and/orinductance of the respective sensor elements changes depending on theamount of the disintegrating gas.

PCT Publication Application No. WO 01/25472 discloses a biosensor usefulto monitor the time and temperature to which a product has been exposed.The biosensor is based on a RF circuit comprising a unit, which changesits conductivity/resistance as a function of time and temperature. Thisunit comprises an enzyme and a substrate, wherein the enzyme is adaptedto affect the substrate so that its conductivity increases as a functionof time and temperature. Thus, a biosensor is disclosed, whose RFcircuit can be activated by applying, for instance, a magnetic fieldover the same to generate a measurable current, which is dependent onthe total resistance of the circuit and which thus varies as a functionof the time and temperature to which the unit of the biosensor has beenexposed.

PCT Publication Application No. WO 95/33991 discloses a conditionindicator for perishable goods. The indicator comprises sensor means forgas or vapor associated with decay or contamination affecting anelectrical property of the sensor means, which are incorporated into anelectrical circuit measuring the property. The electrical circuitdisclosed in WO 95/33991 is not a RF circuit. That means the sensorchanges are not remotely readable. The circuit may be printed. Thesensor may comprise a semiconducting material such as polypyrroles,which change an electrical property such as resistance or impedance onexposure to certain gases.

SUMMARY OF THE INVENTION

The present invention, in some embodiments thereof, relates totemperature sensitive applied materials and devices as temperatureindicators, whether as a threshold, a temperature history or acombination thereof, optionally with a visually and/or instrumentallyvisible summary of the elapsed time-temperature profile the device hadexperienced.

According to at least some embodiments, the devices may optionally betime and/or temperature sensitive devices. Regardless of theirsensitivity, and hence the factor(s) which affect the devices, thedevices may optionally be perceived as being affected by time, in thesense that a visual display on the devices evolves or changes over time,even if both time and temperature optionally affect such a visualdisplay.

According to at least some embodiments, there is provided a promotionalobject, which is a time and/or temperature sensitive device having adisplay that features a coupon or other incentive to stimulate apurchase and/or a visit to a commercial location. Non-limiting examplesof such a commercial location include a store, a restaurant, a movietheatre, a live performance location, a club and the like. The displaymay optionally feature the incentive in a single appearance after a settime or with a multi stage appearance, in which the display changes aplurality of times to feature the incentive(s).

According to at least some embodiments, there is provided a prizeobject, which is a time and/or temperature sensitive device having adisplay that features a prize that is won. The prize may optionally be alottery prize or the like. Optionally, the prize is only indicated asbeing won on certain prize objects, while other objects may optionallyfeature a display indicating a consolation prize or no prize. Thedisplay may optionally feature the prize in a single appearance after aset time or with a multi stage appearance, in which the display changesa plurality of times to feature the prize(s).

According to at least some embodiments, there is provided anentertainment object, which is a time and/or temperature sensitivedevice having a display that features a story in parts or a greetingcard that reveals some type of visual indication over time. Such a storyand/or visual indication may be described as information. Thisinformation can be preprinted or variable; if the latter, optionally theinformation is controlled by the user.

According to at least some embodiments, optionally any of the aboveembodiments may be combined with a time limitation, such that after acertain amount of time has elapsed, the promotion, prize orentertainment display ceases to display the visual indication. Forexample, for an incentive such as a store coupon, the user would need tobring the coupon to the store while the visual indication was stillbeing displayed, thereby incentivizing the user to go to the store morequickly.

According to at least some embodiments, optionally any of thetechnologies described below may be used to implement these devices,non-limiting examples of which are given in Examples 1-4 below, providedafter technology Examples A-P.

In at least some embodiments, the devices may optionally be used fordetermining a temperature status of a temperature sensitive product,such as a perishable good for example. By “temperature status” it ismeant a temperature experienced by the product to which it is thermallycoupled and in equilibrium or pseudoequilibrium, whether as a breach ofa minimum or maximum temperature threshold, a temperature history, atime temperature history or a combination thereof. By a “temperaturehistory” it is meant cumulative exposure to temperature over any givenperiod of time. By “time temperature history” it is meant the collectiveexposure to temperature and elapsed time, as a temperature sensitiveproduct may be expected to suffer from the cumulative effects of bothtemperature and time.

The present invention, in some embodiments thereof, relates to atemperature indicator apparatus, system and method capable of reportinga summary of the elapsed time-temperature history of a good to which itis thermally coupled (a TT). The TTI can provide a summary of theelapsed time-temperature above a pre-set temperature threshold (HTTI),below a pre-set temperature threshold (LTTI), or at all the temperatureranges (TTI).

According to other embodiments, the temperature indicator specificallyprovides an indication as to whether a temperature threshold at, aroundor below a set low temperature point has been breached, withoutproviding a time and temperature history (hereinafter referred to as“freeze indicator” FI).

According to yet other embodiments, the temperature indicatorspecifically provides an indication as to whether a temperaturethreshold at, around or above a set high temperature point has beenbreached, optionally without providing a time and temperature history(hereinafter referred to as “threshold indicator”, TI).

According to yet other embodiments, different indicators are attached toone another, providing both threshold and/or freeze indicationsoptionally without providing a time-temperature history.

Also optionally, different embodiments of temperature sensitive devicesas described herein (TTIs, TIs and/or FIs) may be combined in one labeland/or one device, optionally including providing such a combination onone substrate, for example by printing on a single substrate.

According to yet other embodiments, different indicators provide one“YES”/“NO” indication that accounts for both threshold and freezeindications, optionally without providing a time-temperature history.

According to yet other embodiments, freeze (FI) and/or threshold (TI)indicators are attached to a TTI, providing a time-temperature historyindication that is optionally accompanied by threshold and freezeindications. The latter indications would preferably have a reactiontemperature that is outside of the range the TTI is effectivelymonitoring the freshness of the product to which it is attached.

The TTI device according to at least some embodiments of the presentinvention is configured so as to provide a change in the properties ofthe TTI structure, induced by a time-temperature dependent chemicalprocess in the TTI structure. Such changes in the properties of a TTIstructure may include optical properties and/or electrical properties.

In one embodiment of the invention the TTI comprises two types ofreactants and the process commences when these two types of reactantsare contacted with one another. The first type of reactants (alsoreferred to as the “passive reactant”) comprise of a reactant that uponcontacting with second type of reactants interacts and/or reacts with atleast one of them. The second type of reactants (also referred to as the“active reactant”) comprise of at least one metallic layer, optionallybeing at least a part of an electrical component, in which the at leastone metallic layer is selected such it changes at least an electricalproperty, optionally of the electrical component, at a rate that istemperature dependent or at a rate that time-temperature dependent uponcoming in contact with the passive reactant.

In some embodiments the at least one metallic layer changes at least oneoptical property at a rate that is temperature dependent or at a ratethat time-temperature dependent upon coming in contact with the passivereactant. In other embodiments the at least one metallic layer changesat least an electrical property and changes at least one opticalproperty at a rate that time-temperature dependent upon coming incontact with the passive reactant. The change in electrical propertiesand optical properties may be correlated or non-correlated.

This change in at least an electrical property is detectable as a changein one or more electrical properties of the TTI structure, such as itsinteraction with electromagnetic radiation (emission, reflection,absorption etc.) and/or its interaction with electrons (resistance,conductance, capacitance etc.). The change in at least an electricalproperty may be transmitted to the spectator relying on internal energyresources such as batteries, in the case it is configured as a so-called“active TTI structure”, or by relying on interaction of the TTI withexternal electromagnetic and/or any other source of stimulus in the caseof a so-called “passive TTI structure”. This component of the TTIstructure (passive or active) is initially an electrically conductivecomponent and changes its conductivity as a function of the temperatureand the time after coming in contact with the “passive reactant”.

The change in properties of the TTI structure may also be visuallydetectable, as a change in the interaction of the TTI with light, suchas color, reflectivity, etc.). In this type of embodiments the visualproperties of the TTI change as a function of the time and thetemperature. In some embodiments, the TTI may change its optical andelectrical properties.

As a non-limiting example of changed optical properties, such changedoptical properties may occur when the chemical reaction is selected fromthe group consisting of acid-base reaction, oxidation-reduction reactionand salt forming reaction.

In yet other embodiments, the “passive reactant” is in the form ofinactivated reactant residing dormant on the surface of the “activereactant”. Upon activation of the inactivated and dormant “passivereactant” is activated and the time-temperature process starts.

The term “active reactant”, as compared to a “passive reactant”,signifies a reactant forming, undergoing or being a part of the TTIcomponent of a changeable electrical and/or optical property.

The technology of the present invention relies on a reaction, whichpreferably takes place between at least two reactants, of which one is a“passive reactant” and one is an “active reactant”.

As indicated above, the reaction (process) may involve or be mediated,catalyzed, inhibited and/or induced by additional one or more substances(passive reactant(s)).

Optionally, such additional substances may comprise one or moresubstances affecting diffusion, such as viscous materials. For example,the passive reactant(s) may for example include a viscous substance(termed here “viscous component”) that contains and/or mediatesdiffusion of the passive and/or active reactants to one another at arate that is correlated to the time or at a rate that is correlated tothe time and the temperature.

Alternatively, a viscous substance may be present within or as part ofthe active reactant of the TTI structure, as for example in the case ofa TTI that is in the form of a capacitor as an electrical component: thecapacitor is composed of two electrodes separated by a porous andinsulating medium acting as a spacer. A viscous substance fills thevacancies of the porous medium that is located in between the capacitorplates, and the degree of penetration of this viscous liquid, being afunction of the elapsed time-temperature, changes the capacitance.Similarly, the active component may be composed of several capacitors,the time-temperature history being expressed in the number of capacitorthat have been penetrated and thus “destroyed” by the viscous liquid. Incase at least one electrode of the capacitor transmits visible light andthe viscous substrate liquid is colored one can use this TTI structureas a visual TTI.

The viscous medium may be a normal viscous medium having its viscosityinversely proportional to the temperature (i.e. viscosity increasingwith decreasing temperature) or an abnormal viscous medium having itsviscosity proportional to the temperature (i.e. viscosity increasingwith increasing temperature); see for example R. ANGELINI, G. RUOCCO,Philosophical Magazine, 87, 553-558, 2007 and van Hooy-Corstjens C. S.J., Hohne G. W. H., Rastogi S., Macromolecules, 38, 1814-1821, 2005.

According to other embodiments of the invention, the device comprises atleast two reactants located adjacent to each other (e.g., in contactwith one another), wherein these at least two reactants are selectedsuch that when at least one passive reactant from the at least tworeactants undergoes a phase change, it affects the chemical reactionwith at least one active reactant from the at least two reactants, thereaction effecting a change in an electrical and/or optical property ofa component with which the at least one active reactant is associated.

It should be understood that the term “undergoes a phase change” usedherein signifies local, partial or complete sublimation, or melting, ordissolution, or material penetration, or any of first, second and mixedorder phase transitions, such as glass transition, melting, inversefreezing, inverse melting etc.

If a TTI undergoes a phase transition, as described above then accordingto at least some embodiments, the TTI is a partial historytime-temperature indicator, as the TTI only reacts or records time spentat temperatures above (HTTI) and/or below (LTTI) a set threshold. In thecase of upper threshold temperature indicators (HTTIs), the embodimentmay include a viscous passive reactant solution that freezes below a settemperature (viscosity increases significantly, and sometimes abruptly,upon lowering the temperature such that below a set temperature itsprocess is practically stopped).

In yet other embodiments for lower threshold temperature indicators(LTTIs), the embodiment may include a viscous passive reactant solutionthat practically freezes above a set temperature (viscosity increasessignificantly, and sometimes abruptly, upon elevating the temperaturesuch that above a set temperature its process is practically stopped).The later embodiment may rely, on a phenomenon termed “inverse freezing”and “inverse melting”.

As indicated above, the device may include a viscous component as asecond “passive reactant”, which may be at the outer surface of thedevice; or may be present in or with the “active reactant”. The viscouscomponent may or may not have a solid-to-liquid transition attemperatures that are relevant to the specific application andconsequently monitor partial or full time-temperature history. Theviscous component is characterized by that when upon exposure totemperatures higher/lower (for normal and inverse freezing systemsrespectively) than a certain threshold temperature specific for theviscous component, it undergoes a change in its mobility and/orviscosity and/or ability to dissolve and transport other chemicalsubstances as well as propagate, for example in porous solids, such as,but not limited to, for example glass powder packed in a tube. Thiscertain temperature (which may for example optionally comprise afreezing point) may be selected to be within a temperature rangerelevant for a specific application of a TTI device and thus the use ofthis viscous component provides for partial time-temperature historyindication: below/above (for normal and inverse freezing systemsrespectively) this temperature, there is no measurement oftime-temperature changes, e.g., since the viscous component is a solidand has no (or very low) time-temperature dependence of mobility untilreaching the temperature. Alternatively, the viscous component may beselected with such a threshold temperature well outside the relevanttemperature range thus providing for full time-temperature historymeasurements.

The TTIs and/or TI and/or FI device is preferably appropriately designedto prevent the chemical reaction from occurring unnecessarily when thedevice is inoperative, and allow the development of thisprocess/reaction when the device is put in operation. This may beachieved by initially placing the entire TTI and/or TI and/or FIstructure in a sealed enclosure, which is configured to allow breaking,removing or puncturing thereof to thereby expose the TTI and/or TIstructure to the environmental changes. Another option is to use anadhesive-type viscous polymer or placing a viscous polymer on a label,thus attaching the viscous component to the other part of the TTI(active reactant, or active and passive reactants) and/or TI and/or FI,which is inactive without the viscous component.

Yet another option is to place a passive reactant (e.g., viscouscomponent) in a sealed reservoir, so that it is separate from the activereactant, and when the TT and/or TI and/or FI device is to be put inoperation, removing the sealed enclosure and attaching the reservoir tothe other part of the TTI (active reactant, or active reactant and asecond passive reactant) and/or TI and/or FI to thereby allowpenetration of the passive reactant (e.g., viscous component) from thereservoir to the other part of the TTI and/or TI and/or FI.

In yet another embodiment, the TTI device, while being inoperative, iskept at a temperature in which the TTI structure (i.e., passivereactant(s) and/or possibly also active reactant(s)) is either inactiveor substantially inactive; and to put the device in operation, it isexposed to the relevant temperature range. In all the abovementionedoptions, the viscous component may serve by itself to induce the timeand temperature changes in the active reactant or may include yet atleast another one passive reactant that induces the time and temperaturechanges in the active reactant.

The active reactant may optionally be an electrically conductivematerial within an electric circuit. The electrically conductivematerial may be patterned to form the features of a component that canbe part of a RF tag (antenna, resistor, capacitor etc.). The chemicalreaction thus causes time and temperature dependent changes in thecircuit of the tag. The RF circuit pattern may be produced by any knownsuitable technique, e.g., printing (e.g., ink jet printing), CVD, PVD,sputtering, patterning (e.g., molding and cutting/etching),electro-deposition, electroless deposition etc. The device may beconfigured as a multi-layer structure (hybrid structure), including afirst substrate layer of an electrically insulting (and possiblyoptically transparent) material, carrying a second layer structure of acomponent formed by the active reactant (electrically conductive layer;or a layer structure patterned to form a capacitor or a resistor etc.),and possibly also a third layer of passive reactant material. The devicemay also include an uppermost layer of an optically transparent andelectrically insulating material.

According to at least some embodiments, time-temperature indicator (TTI)and/or threshold temperature (threshold (TI) and/or freeze (FI)) devicesare characterized in that the electrical component is selected from thegroup consisting of conductor resistor, capacitor, diode, inductancecoil and antenna. It is especially preferred that the electricalcomponent is configured as at least one element of an RF circuit or asat least one component that can electrically interact with an RFcircuit.

The electrical embodiment may optionally be combined with the viscoussubstance as follows. Considering a capacitor component formed by twometal/conductive layers that are separated by a porous medium having acertain dielectric constant, a viscous component may be used as apassive reactant to penetrate the porous component at a rate that istemperature dependent or at a rate that is time-temperature dependentand thereby cause either a sudden or increasing short (change inresistance between these two metal/conductive layers) in the capacitoror a gradual change in the capacitance due to the difference in thedielectric constants of the pure porous medium and the porous mediumfilled with the viscous component.

According to at least some embodiments, a barrier is provided betweenthe active and passive reactants, the barrier layer may serve as adiffusion layer for the passive reactant, thereby providing yet anothertype of time-temperature process for the TTI device, according to whichthe measured time-temperature history is determined. In order for thepassive reactant layer to become in contact with the active reactantlayer, the first time-temperature dependent process involves propagationof the passive reactant through the barrier, followed by the reactionand/or interaction between the passive reactant and active reactant.

In yet other embodiments of the invention the TTI comprises at least twotypes of reactants, including at least one “passive reactant” (areactant that upon contacting with second type of reactants (activereactants) interacts and/or reacts with at least one of them, changingat least an optical and/or an electrical property of the TTI), and atleast one “active reactant” in the form of a metallic layer, selectedsuch it changes at least an electrical property or an optical propertyat a rate that is temperature dependent or at a rate thattime-temperature dependent upon coming in contact with the passivereactant.

Optionally, such a metallic layer is covered with a barrier or barrierlayer. Without wishing to be limited by a single hypothesis, addition ofthe barrier layer yields two effects, one being the retardation of thecommencement of the interaction and/or reaction between the “activereactant” and “passive reactant”, rendering the rate of the reaction ofthe TTI time-temperature dependent, while the other is expressed in thealteration of the rate and its temperature dependence of reaction and/orinteraction between the “active reactant” and “passive reactant”. Themagnitude of the retardation as well as rate and temperature sensitivityalteration of the process depends on the nature of the barrier layer.Barrier layers are normally made of polymers and are therefore easilyprintable on the surface of the at least one “active reactant” in theform of a metallic layer. Alternatively, such barrier layers may beformed during production of the TTI, for example using flexographyprinting of a mixture of monomers thereof and polymerizing them using,UV, EB and the like.

Again without wishing to be limited by a single hypothesis, optionallybarriers are constructed such that the reaction of the passive andactive reactants does not provide a simple exponential decay but ratherresults in a hysteresis, followed by a first exponent decay. In othercases, the barriers are constructed to exhibit a rather short hysteresisand a non-first order decay. The specific nature of the time andtemperature dependence of the TTI operation depends on the nature of thebarrier.

The addition of a barrier layer optionally permits visualization of thetime-temperature count using a plurality of TTI segments each having adifferent thickness and/or composition. In such TTIs, the segments willchange optical and/or electrical properties one after the other,providing a clear presentation of both passed time-temperature as wellas remaining time-temperature and/or time at any given temperature.

According to various embodiments, activation energy (and/or thetemperature sensitivity of the process) and hence lifespan of the TTI(ie—the time period during which temperature history is recorded) mayoptionally be controlled according to the amount and type of reactants,and also according to the selected barrier.

Optionally and preferably, the barriers may be printed as for any otherlayer, as described herein in more detail. Optionally, such printingenables a multi-step TTI to be prepared from such printed layers.

According to various embodiments of the TTI with a barrier, thethreshold indicator may optionally comprise colored crystals, and/orcolorless crystals and colored powder dissolved and/or mixed in itand/or colorless crystals of acid/base and acid/base indicators.

Another embodiment of the present invention relates to a printing ink orprinting ink concentrate, comprising the at least one active reactant,the at least one first passive reactant and/or the at least one secondpassive reactant of the above-described time-temperature indicatordevices.

Yet another embodiment of the present invention relates to a packagingmaterial or a label, comprising at least one of the above-describedtime-temperature indicator devices.

As used herein, the term “viscous” may also optionally relate toviscoelastic or Newtonian liquids.

As used herein the terms “good” and “product” are used interchangeablyto refer to a physical item or object, or collection of physical itemsor objects.

In some embodiments, the TTI is in a form selected from the groupconsisting of a surface coating, a flexible film, a patch, a label, apouch, a sachet, a liquid, an adhesive and an ink component.

In some embodiments, the product to which the TTI is coupled is selectedfrom the group consisting of an edible product, a pharmaceuticalproduct, a nutraceutical product, a cosmetic product and a cosmeceuticalproduct.

According to at least some embodiments, there is provided a timetemperature indicator (TTI) which is capable of providing a summary ofthe time and temperature history, comprising an active reactant layer, apassive reactant layer and a release layer, wherein the release layerseparates the active reactant layer from the passive reactant layer, andwherein physical removal of the release layer enables the activereactant layer to contact the passive reactant layer and to startindicating the summary of time and temperature history.

Optionally the active reactant layer comprises a metallic layer andwherein the passive reactant layer comprises an etchant for etching themetallic layer.

Optionally the metallic layer comprises aluminum and the etchantcomprises a pressure sensitive adhesive comprising a polyacrylicpolymer, an aluminum etching acid, an antifoaming agent and flatteningagent.

Optionally the TTI further comprises a backing layer, the backing layercomprising an adhesive.

Optionally the TTI further comprises a front layer, comprising a visualindicator.

Optionally the summary of time and temperature history is indicatedthrough an optical indication appearing upon etching of the metalliclayer by the etchant.

Optionally the front layer further comprises a visual indicator thatdoes not change with time and/or temperature, the TTI further comprisingan impervious barrier under the visual indicator.

Optionally the impervious barrier is impervious to a reaction betweenthe etchant and the metallic layer and comprises UV curable ink.

Optionally the summary of time and temperature history is indicatedthrough an electrical indication appearing upon etching of the metalliclayer by the etchant.

Optionally the TTI further comprises a viscous substance acting as abarrier to reaction between the passive and active reactants.

Optionally the passive reactant comprises a viscous substance.

Optionally the TTI further comprises a water resistant coating.

Optionally the water resistant coating comprises PVDC, silicon oxide,aluminum oxide, other oxides, polychlorotrifluoroethylene (PCTFE),polyvinyl fluoride and alike

Optionally the TTI is adapted to provide a summary of the elapsedtime-temperature above a pre-set temperature threshold (HTTI), below apre-set temperature threshold (LTTI), or at all the temperature ranges(I).

Optionally the TTI further comprises an additional material thatprovides an indication that a temperature threshold at, around or belowa set low temperature point has been breached, wherein the additionalmaterial does not provide information regarding a time and temperaturehistory.

Optionally the TTI further comprises an opal structure.

Optionally the TTI further comprises an inverse opal structure.

Optionally the TTI further comprises an inverse melting material.

Optionally the TTI further comprises an additional material thatprovides an indication that a temperature threshold at, around or abovea set high temperature point has been breached, wherein the additionalmaterial does not provide information regarding a time and temperaturehistory.

Optionally the at least one material comprises lauric acid.

Optionally the at least one material comprises a combination of4′-Amino-N-methylacetanilide and phenol red.

Optionally the indication comprises a change in electrical and/oroptical properties of the at least one material.

Optionally the TTI further comprises a perishable good for beingattached to the TTI.

Optionally the TTI further comprises a temperature history indicator,attached to the TTI.

According to at least some embodiments there is provided a thresholdfreeze indicator, comprising an inverse viscosity freeze materialcapable of providing an indication as to whether a minimum temperaturethreshold has been breached or provide indication to the elapsed thatoccurred upon exposure to a set temperature.

Optionally the indicator material comprises an inverse melting or aninverse freezing material.

Optionally the indicator further comprises two conductive layersseparated by a porous layer, wherein the freeze indicator materialpasses through the porous layer at a rate that is inversely temperaturedependent, advancing more quickly at lower temperatures.

Optionally the freeze indicator material is solid or undergoesnon-linear increase of viscosity above a certain temperature or above acertain temperature range.

According to at least some embodiments there is provided a thresholdfreeze indicator (FI), comprising a photonic crystal constructioncapable of providing an indication as to whether a minimum temperaturethreshold has been breached.

Optionally the FI further comprises an opal structure.

Optionally the opal structure comprises ordered nanospheres immersed inwater.

Optionally the FI further comprises an inverse opal structure.

Optionally the inverse opal structure comprises ordered nanocontainerscontaining water, produced from ordered nanospheres.

Optionally the nanospheres comprise polymer beads or inorganic oxidematrix.

Optionally the FI further comprises heavy water or water/heavy watermixtures.

Optionally the FI further comprises adding salt and/or an organicsolvent to control the temperature of the minimum temperature threshold.

According to at least some embodiments there is provided an inverse TTI(time temperature indicator) for providing a time temperature history,comprising a porous medium, an inverse melting material, a destroyableseal and an inspection window; wherein the porous medium is separatedfrom the inverse melting material by the destroyable seal, and whereinupon destruction of the destroyable seal, the inverse melting materialenters the porous medium and provides an optical indication of the timetemperature history.

Optionally the optical indication comprises a visual indication.

Optionally the inverse melting material comprises alpha-cyclodextrin(alpha-CD), water and 4-methylpyridine (4MP).

Optionally the inverse TTI further comprises a visible dye for providingthe visual indication.

As used herein the term “about” refers to ±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”. The term“consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a” “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a biomolecule” or “at least one biomolecule” may include aplurality of biomolecules, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawings will be provided by the Office upon request and paymentof the necessary fee.

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings and images.With specific reference now to the drawings and images in detail, it isstressed that the particulars shown are by way of example and forpurposes of illustrative discussion of embodiments of the invention. Inthis regard, the description taken with the drawings and images makesapparent to those skilled in the art how embodiments of the inventionmay be practiced. For the avoidance of doubt, it is understood that thedrawings are not necessarily shown to scale.

In the drawings:

FIGS. 1A-1 and 1A-2 presents schematic illustrations of an exemplary TTIand its resulting kinetics at different temperatures according to atleast some embodiments of the present invention;

FIG. 1A-3 shows an exemplary TTI that features both a thresholdindicator (TI) and a time-temperature history indicator (TTI);

FIG. 1B shows the gradual development of two different examples of TTIcombined with TI and FI residing on the same spot (the three panels ofthe rectangle label and two panels of the round label on the left side),as well as two panels (both for the rectangle and round labels) showingstates in which the product should not be used (two panels on the rightside);

FIG. 1C shows a different implementation of the metal based TTI of FIG.1A-1 according to at least some embodiments of the present invention,having the passive and active layers attached to one another in theunactivated form of the TTI, allowing its activation by pulling releaselayer and combining the layers;

FIGS. 2A-1, 2A-2, 2B-1 and 2B-2 show schematic illustrations of only thethreshold indicator component alone (before and after crossing thepre-set threshold temperature) according to various embodiments of thepresent invention;

FIG. 3 shows the kinetics of a TTI made of aluminum (OD=0.6) on PET filmat 4 C as a function of the water content in the passive reactant;

FIG. 4 depicts the color of an active spot of an aluminum (OD=0.6) basedTTI having no barrier as a function of the time after activation, whileFIG. 5 graphs the color changes as a function of the time afteractivation of a label that was stored at a constant temperature of 4 C.

FIG. 6 depicts the time to reach end point as a function of the printthickness (expressed as the sum of anilox size of the printingstations). The graph on the right shows the kinetics of selected pointsof the graph on the left (color values as a function of the time at 37C).

FIG. 7 depicts an embodiment of a three-spot time-temperature indicatorhaving three trapezoid spots, each having a different barrier thickness,at different times after activation, when kept at constant temperatures.

FIG. 8 depicts an example of how printing series of barriers made of thesame monomer composition but having different proportions yielddifferent time-temperature behavior of the TTIs.

FIG. 9 depicts the density of H₂O as a function of the temperature. Thisanomalous phenomenon was used in the past for building freezeindicators;

FIG. 10 presents the viscosity of different mixtures ofalpha-cyclodextrin (alpha-CD), water and 4-methylpyridine (4MP) (molarratio provided in graph) as a function of the temperature; The resultsof mixing various salts with water are shown in FIG. 11, while theresults of mixing the organic solvent methanol or the salt sodiumchloride with water are shown in FIG. 12.

FIG. 13 shows an exemplary, illustrative, non-limiting thresholdindicator based upon diffusion;

FIG. 14 shows an exemplary label having the layer structure of FIG. 13before (left) and after (right) activation (i.e. before and aftercrossing the threshold temperature);

FIG. 15 shows an exemplary, non-limiting illustrative thresholdindicator based upon metal etching;

FIG. 16 shows the threshold indicator of FIG. 15 in a schematic diagramof an exemplary label;

FIG. 17 shows a TI label having the layer structure of FIG. 16 beforeand after activation;

FIG. 18A shows an exemplary inverse freeze indicator (FI) label whileFIG. 18B shows this exemplary label in a schematic cross sectionaldiagram;

FIG. 19A depicts a cross section of a non-limiting, exemplary,illustrative TTI label according to the embodiment in which the TTIprovides a summary of the elapsed time-temperature, optionally in theform of a disappearing signal;

FIG. 19B depicts an alternative TTI structure of the embodiment of FIG.19 where the top layer is the aluminized polymer film;

FIG. 20 depicts a non-limiting, exemplary, illustrative TTI with adisappearing signal according to at least some embodiments.

FIG. 21 shows molecules which may optionally be used for the production(for example, by flexography printing and UV curing) of a non-limiting,exemplary, illustrative impervious barrier for a TTI.

FIG. 22 depicts labels with and without the impervious barrier atdifferent temperatures;

FIG. 23 depicts the CIE-Lab color values of the non-functional yellowpart of TTI labels as a function of the time after activation with andwithout impervious barrier printed under the non-functional areas of thelabels;

FIG. 24 depicts the kinetics of two TTI labels immersed in water at 4 C,of which one contains a top PVDC coating while the other does not;

FIG. 25 shows results for different compositions forming the activematerial of non-limiting embodiments of freeze indicator;

FIG. 26 shows an exemplary Threshold-60 VI Label;

FIG. 27 shows a differential scanning calorimetry graph of Myristicacid.

FIG. 28A shows an inverse opal photonic crystal containing an aqueoussolution; FIG. 28B shows an exemplary FI based upon this technology.FIG. 28C shows this exemplary FI in a schematic cross sectional diagram.

FIG. 29 shows an exemplary technology for a FI based upon inversemelting.

FIGS. 30A1, 30A2 and 30B show exemplary inverse TTIs based upondiffusion.

FIGS. 31 A-D show schematic block diagrams of exemplary light to darkTTI devices according to at least some embodiments of the presentinvention;

FIG. 32A shows such an exemplary light to dark TTI device in a label,indicating the effects of elapsed time;

FIG. 32B shows a graph of CIE-Lab color value of the active spot for anexemplary light to dark TTI device;

FIG. 32C shows a graph of CIE-Lab color value of the active spot for aTTI device that is “dark to light” as described above;

FIG. 33 shows an exemplary FI based upon breaking a sealed containerupon freezing; and

FIG. 34 shows the optical density as a function of the time afteractivation of an aluminized TTI label having an alkali solublepolyacrylate polymer printed atop the active aluminum spot by means offlexography.

FIGS. 35A, 35B, 35C, 35C-1, 35D and 35D-1 show a non-limiting, exemplarydetailed implementation of a promotional object according to at leastsome embodiments of the present invention;

FIG. 36 depicts a multi spot promotional object according to at leastsome embodiments of the present invention.

FIG. 37 shows a multi segment object made according to theabovementioned technologies according to at least some embodiments, withdifferent segments showing different visual indications at differenttime intervals after activation.

FIGS. 38A-C shows an object according to at least some embodiments inwhich a single spot reveals latent information after a certain timeafter activation and then after yet another time interval the revealedinformation fades and disappears.

FIG. 39 presents a cross section of a non-limiting example of an objectof FIG. 38.

FIGS. 40A-D depict an object in which a plurality of spots reveal latentinformation at different time intervals after activation and then afteryet additional time intervals the revealed information exposed in thedifferent spots they fade and disappear.

FIG. 41 shows the object of FIG. 40 in cross-sectional detail.

FIGS. 42A-C show an exemplary promotional object in which a single spotreveals latent information after a certain time after activation and therevealed information fades slowly or does not fade at any time that isrelevant to the function of the promotional object.

FIG. 43 presents a cross section of a non-limiting example of apromotional object of FIG. 42.

FIGS. 44A-D show a promotional object 103 in which information isrevealed in some spots and remains, while such information is revealedin other spots but disappears within a functionally relevant timeperiod.

FIG. 45 shows the promotional object 103 of FIG. 44 in cross-section.

FIGS. 46A-C show a high temperature activated promotional object basedon melting of an etchant composition and etching of a layer.

FIGS. 47A-C show a high temperature activated promotional object.

FIGS. 48A-B show a non-limiting example of an entertainment object as agreeting card.

FIGS. 49A-G show another non-limiting example of an entertainment objectas a multiple choice story.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to anapparatus, system and method for a time temperature indicator (TTI)which is capable of providing a summary of the time and temperaturehistory of a good to which it is coupled, optionally including withregard to providing an indication as to whether one or more temperaturethresholds have been breached.

According to other embodiments, the TTI specifically provides anindication as to whether a temperature threshold at or around the freezepoint has been breached, optionally even without providing a time andtemperature history.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details set forth in the following description orexemplified by the Examples. The invention is capable of otherembodiments or of being practiced or carried out in various ways.

According to at least some embodiments, there is provided a device whichincludes a substance that has a light characteristic that is alteredirreversibly as a function of time and temperature; hence it is used todetect and reflect the time-temperature history to which the product hasbeen exposed. Optionally, rather than a summary of the history, thedevice detects and reflects an indication as to whether a temperaturethreshold at or around the freeze point has been breached, optionallyeven without providing a time and temperature history.

The phrase “light characteristic”, as used herein, refers to anintrinsic or an acquired capacity of a substance to interact with light,including emitting, radiating, absorbing, filtering, bleaching,quenching, refracting and/or reflecting.

Examples of a light characteristic include, without limitation, colorand chromogenic activity, luminescence, photoluminescence, (e.g.,fluorescence, phosphorescence), transparency and reflectivity, includingintensities thereof and lifetimes thereof, where applicable.

Thus, according to some embodiments of the present invention, a lightcharacteristic of the probe can be the color and chromogenic activity ofthe substance and/or its intensity and/or its integrated intensity, thephosphorescence lifetime and/or phosphorescence intensity and/orintegrated intensity, and/or the fluorescence intensity and/orfluorescence lifetime, and/or lag time before discoloration, and/or loseof luminescence, and/or discoloration rate, and/or rate of loss of theluminescence, and/or reappearance of color of the probe (coloration),and/or rate of appearance of color of the probe, and/or reappearance ofluminescence of the probe, and/or rate of appearance of luminescence,and/or color shift (change) of the probe and/or rate of color shift ofthe probe and combinations thereof.

Luminescence is a phenomenon in which energy is absorbed by a substance,commonly called a luminescent material, and emitted in the form oflight. The absorbed energy can be in a form of light (photons),electrical field or colliding particles (e.g., electrons). Thewavelength of the emitted light differs from the characteristicwavelength of the absorbed energy (the characteristic wavelength equalshc/E, where h is the Plank's constant, c is the speed of light and E isthe energy absorbed by the luminescent).

The luminescence can be classified according to the excitation mechanismas well as according to the emission mechanism. Examples of suchclassifications include photoluminescence, electroluminescence,fluorescence and phosphorescence. Similarly, luminescent materials areclassified into photoluminescent materials, electroluminescentmaterials, fluorescent materials and phosphorescent materials,respectively.

A photoluminescent material is a material which absorbs energy in theform of light, an electroluminescent material is a material whichabsorbs energy in the form of electrical field, a fluorescent materialis a material which emits light upon return to the base state from asinglet excitation, and a phosphorescent materials is a material whichemits light upon return to the base state from a triplet excitation.

In fluorescent materials, or fluorophores, the electron de-excitationoccurs almost instantaneously, and the emission ceases when the sourcewhich provides the exciting energy to the fluorophore is removed.

In phosphorescent materials, or phosphors, the excitation state involvesa transformation to a spin state which decays only slowly. Inphosphorescence, light emitted by an atom or molecule persists after theexciting source is removed usually for a longer time than the respectivefluorescence.

The phrases “visible light”, “visible spectrum” and “optical spectrum”,as these are used herein interchangeably, describe the portion of theelectromagnetic spectrum that is visible or can be detected by thetypical human eye, and thus electromagnetic radiation in this range ofwavelengths is called visible light. A typical human eye can detect, andas a result the human brain can perceive, wavelengths in air from about380 nm to about 750 nm.

The term “ultraviolet” or “UV”, is used herein to describe a portion ofthe electromagnetic radiation (light) spectrum, spanning wavelengthsshorter than that of visible light and longer than X-rays, andencompasses all subranges of UV, as listed in the table below.

Wavelength Energy per Name range photon Ultraviolet A (long wave, blacklight, UVA) 400 nm-315 nm 3.10-3.94 eV Near UV (NUV) 400 nm-300 nm3.10-4.13 eV Ultraviolet B (medium wave, UVB) 315 nm-280 nm 3.94-4.43 eVMiddle UV (MUV) 300 nm-200 nm 4.13-6.20 eV Ultraviolet C (short wave,germicidal, 280 nm-100 nm 4.43-12.4 eV UVC) Far UV (FUV) 200 nm-122 nm6.20-10.2 eV Vacuum UV (VUV) 200 nm-10 nm  6.20-124 eV  Extreme UV (EUV)121 nm-10 nm  10.2-124 eV 

As used herein, the term “chromophore” refers to a substance, or a partthereof, that is characterized by a color, such as a colorant, dye or apigment, as those which are typically used in, for example, inks andpaints, and which change in response to temperature. According to someembodiments of the invention, such changes can be detected by the nakedeye and/or by various spectrophotometric measurements.

Exemplary food products include natural, whole, raw, fresh, cooked,solid, liquid, liquefied, dried, powdered and otherwise processed plant-or animal-derived food products which provide a source of protein, fat,carbohydrates, vitamins and/or minerals for general sustenance ofliving, such as, for example, meats, fin-fishes, shell-fishes, dairyproducts, eggs, fruits, vegetables, honey, grains, herbs, nuts, coffee,tea and food additives, and any combination thereof. Specifically, theunits, systems, articles and methods presented herein are useful in thefood manufacturing, processing, distributing and retail industries tomonitor the freshness and general quality of raw materials as well asfinished goods, such as fresh meat and fish which are prone to oxidationor decomposition by microorganisms.

Exemplary nutraceutical products include, but are not limited to,powders, syrups, gels, tablets, pills, capsules and/or other forms offood additives, dietary supplements, probiotic products containing livebeneficial microorganisms (e.g., probiotic microorganisms), food derivedproducts or food extracts, typically used to enhance, improve, maintainor protect human well being and health.

Exemplary pharmaceutical products include, but are not limited to,tablets, pills, capsules and/or other forms of encapsulated, as well asbulk powdered, pelletized and granulated pharmaceutical substances,liquid pharmaceutical substances such as drug solutions, blood, serums,plasma and other bodily fluids and products thereof, or solidpharmaceutical substances used for the treatment of human or animalailments or diseases.

Pharmaceutical products therefore encompass drugs for internalconsumption via, for example, oral or systemic administration.

Pharmaceutical products further encompass, for example, bodily organs ortissues to be implanted in a subject, including blood and componentsthereof, liver, heart, cornea, retina, and the like, which should bemaintained at an appropriate temperature and without breaching one ormore temperature thresholds during the transplantation process.

Thus, exemplary temperature-sensitive products encompass drugs, cosmeticand cosmeceutical products for topical, nasal, mucosal, ophthalmicadministration, for administration by inhalation and/or foradministration via any other route.

Exemplary cosmetic and cosmeceutical products include, but are notlimited to, products in the form of solutions, oils, ointments, pastes,gels, lotions, milks, suspensions, powders, aerosols, sprays, foams,shampoos, hair conditioners, lacquers, makeups, solid sticks andtoothpastes.

An exemplary list of cosmetic and cosmeceutical products that canbenefit from the methodology described herein include, withoutlimitation, lip glosses, lipsticks, toothpastes, hair products and nailpolish/lacquers.

According to at least some embodiments, the present invention features aTTI alone, a threshold indicator alone or a combination thereof.

Threshold indicators are single-use disposable indicators that are aimedat reporting a temperature excursion to temperatures that are above aset limit. Threshold indicators are used to monitor products that can bedamaged when exposed to high temperatures, such as vaccines and otherbiological macromolecular materials that tend to undergo denaturation atelevated temperatures. The threshold indicator is designed to undergo anirreversible and tamper-resistant color change when exposed totemperatures above a set limit.

Overview and Metal Based TTI Devices

Turning now to the drawings, FIG. 1 (with multiple parts) shows anoverview of metal-based TTI devices and also some threshold indicators.

FIG. 1A-1 presents a schematic illustration of an exemplary TTIaccording to at least some embodiments of the present invention, whileFIG. 1A-2 shows the kinetics of the behavior of this exemplary TTI.

FIG. 1A-1 shows a schematic diagram of an exemplary metal-based TTI witha plurality of layers. A 36 μm transparent PET film (100) coated withaluminum (PVD, O.D=0.6) (101) was loaded on a flexography machine(Arsoma 410S, Gallus) and the aluminum side was printed with threelayers of a UV curable colorless primer (UVT 00041, Flint) (102, 103,104), each of which hereinafter referred to as a barrier, forming astaircase-like layered film of increasing thickness. The web was thenprinted with three layers of white and one layer of yellow (105),leaving three openings in the form of trapezoid rectangles in a way thateach trapezoid reveals a different layer of UV curable colorless primer(trapezoid openings 106, 107 and 108 exposing layers 102, 102+103 and102+103+104 respectively). It should be noted that FIG. 1A is not drawnto scale and that while the width of the trapezoid openings is normallyin the mm range, the thickness of the barrier and aluminum layerstypically is in the range of nm to microns. The first side of the labelwas finished by adding pictograms and logo. The web was then inverted onthe machine and one layer of primer, one layer of yellow then two layersof white were printed sequentially atop the PET side (all layerscombined in 109). The web was then covered with a pressure sensitiveadhesive at the PET side (110) terminated with a siliconized releaselayer (111), slit and die cut, forming finished “active reactant” labels(112).

The “passive reactant” label of a TTI was produced on a reverse gravurecoating machine. A 36 μm transparent PET film (113) was coated with a 25μm thick layer of a mixture of a pressure sensitive adhesive andphosphoric acid (114). The web was then terminated with a siliconizedrelease layer (115), slit and and die-cut into finished labels (notshown).

The TTI was activated by adhering a “passive reactant” label to thealuminum side of the “active reactant” label. Again, it should be notedthat FIG. 1A-1 is not drawn to scale and that while the width of thetrapezoid openings is normally in the mm scale, the thickness of thebarrier and aluminum layers is typically in the range of nm to microns.Consequently, the gaps between the barrier layers and the adhesive layerdo not appear in reality. Initially, the three trapezoid spots had amirror-like, shiny appearance. In a next step, the metallic surfaceslose their shiny appearance and turn dark. As time-temperature elapses,the aluminum layer is consumed sequentially, one trapezoid after theother (that is, the trapezoid openings are consumed in the followingorder: trapezoid openings 106, then 107, then 108 in the above describedcase) revealing the yellow color underneath. The color progressionprocess normally does not follow a single exponent decay but is rathercharacterized by a lag period, with a duration that depends on thecomposition and thickness of the printed barrier and the temperature.Next, the color change progresses at a rate that is temperaturedependent, often resembling a single exponent decay. In other embodimentthe color change of this step resembles more of a staircase.

The results of this functionality and set of layers are shown in FIG.1A-2 showing the color change as a function of the time of a TTI labelthat is a combination of (112) and the previously described die-cutlabel at stored at 4 C. Black rectangles show the rate of color changeof the first trapezoid having a very thin barrier, red circles show therate of color change of the second trapezoid having thicker barrier andblue triangles show the rate of color change of the third trapezoidhaving even thicker barrier.

FIG. 1 A-3 shows an exemplary TTI that features both a thresholdindicator and a time-temperature history indicator (in both non-limitingexamples, the threshold indicators cause the word “EXPIRED” to becomevisible, for example optionally in red letters (latent before crossingat least one of the threshold temperatures). It should be noted that thethreshold indicators turn-on may be expressed in other words and/orsymbols and may come in one symbol or a plurality of symbols, separatedor together (for example as presented in the figure).

According to at least some embodiments, the threshold indicator developsat a precise temperature point, but alternatively may develop in a rangeof a few degrees on either side of this precise temperature point,according to the material used and the thermal coupling between theperishable good and the temperature sensitive material. As non-limitingexamples, the temperature point may optionally be selected from −40 C to+100 C, preferably is selected from −10 to 60 C and more preferably isin the range of at least +2 to +8° C. The time required for thethreshold indicator to develop is optionally between a fraction of asecond to several hours and even days and months, depending onconfiguration and embodiment.

FIG. 1B shows the gradual development of the TTI history part of theindicator (the three panels on the left side), as well as three panelsshowing states in which the product should not be used (three panels onthe right side), which include such conditions as the threshold havingbeen breached and/or the history showing that a combination of time andtemperature indicates that the product should not be used.

FIG. 1C shows a different implementation of the metal based TTI of FIG.1A-1 according to at least some embodiments of the present invention,with only one barrier layer, with the active layer and passive layerattached to one another in a way that allows activation of the TTI bysimply removing a liner barrier and subsequently combining the twolabels.

FIG. 3 shows the kinetics of a TTI made of aluminum (OD=0.6) on PET filmat 4 C as a function of the water content in a pressure sensitiveadhesive layer containing phosphoric acid (PSA) with the phosphoric acidserving as the passive reactant layer. As can be seen, in this case, theTTI's lifespan is shortened when the water content of the PSA increases.

FIG. 4 depicts the color of an active spot of an aluminum (OD=0.6) basedTTI having no barrier as a function of the time after activation, whileFIG. 5 graphs the color changes.

FIG. 6 depicts the time to reach end point as a function of the printthickness (expressed in the sum of anilox volumes of the differentaniloxes used for printing the barrier). The graph on the right showsthe kinetics of selected points of the graph on the left.

FIG. 7 depicts an embodiment of a three-spot time-temperature indicatorhaving three trapezoid spots, each having a different barrier thickness,at different times after activation, when kept at constant temperatures.

FIG. 8 depicts an example of how printing series of barriers made of thesame monomer composition but having different proportions yielddifferent time-temperature behavior of the TTIs.

TTI Device Based Upon Disappearing Visual Information

Yet another preferred embodiment of a TTI of the present inventionexhibits the summary of the elapsed time-temperature in the form of adisappearing signal. FIG. 19A depicts a cross section of a non-limiting,exemplary, illustrative TTI label according to this optional butpreferred embodiment. The label is activated, meaning that the etchinglabel was placed in contact with the aluminum label and thetime-temperature history is being determined. Optionally, if the barrieris printed on top of the aluminum layer with an optical and/or visualindication, then the barrier will show a disappearing signal. In othercases where the barrier is printed above all the region of the aluminumthat is seen to the eye there will not be a signal appearing anddisappearing. Both have the same cross section but for the purposes ofdescription, FIG. 19A is assumed to show a disappearing signal.

Yet another possibility is to construct the TTI in the form disclosed inFIG. 19B. The label of FIG. 19A normally bears an adhesive on the sideof the aluminized film, attached to layer 4 and a liner layer to protectit until adhesion to the product to be monitored. Inspection of thecondition of such a label is done normally through the transparentpolymer film 10 that is bearing the etchant composition. In the case ofthe TTI depicted in FIG. 19B the TTI actually bears an adhesive on theside of the film bearing the etchant composition, attached to layer 4and a liner layer to protect it until adhesion to the product to bemonitored. Inspection of the condition of such a label is done normallythrough a transparent polymer film 6 that is bearing the aluminum layer5 (layers having the same numbers in FIG. 19B are the same material(s)as in FIG. 19A).

FIG. 20 depicts a non-limiting, exemplary, illustrative TTI with adisappearing signal (visual indication) according to at least someembodiments described herein in which the TTI exhibits the summary ofthe elapsed time-temperature in the form of a disappearing signal.Specifically, FIG. 20 shows X and V TTI labels according to theembodiment 1) just after activation, 2) after expiry of the firsttime-temperature segment, and 3) after expiry of the second and lasttime-temperature segment.

According to this embodiment a metalized (aluminum, PVD, OD=0.6, 6 inFIG. 19) PET film (36 μm, layer 5 in FIG. 19) is coated on the PET sidewith process yellow (two layers, anilox 10/180, layers 1 and 2 in FIG.19) then process white (two layers, anilox 10/180, layers 3 and 4 inFIG. 19). Optionally, a layer of aluminum may also be printed afterlayer 4 to increase light opacity of the back printing. This layer mayallow printing of fewer ink layers on the back of the label. The web isthen optionally and preferably inverted, and the aluminum side of thelabel is printed with the desired graphics and pictograms (layer 7 inFIG. 19), to preserve the aluminum. A barrier layer (layer 8 in FIG. 19)is then printed in a way that after activation the active area of thelabel has a metallic appearance, but without any additional visibleshape on it except for pre-printed graphics and pictograms (shown as X1and V1 in FIG. 20 for the sake of illustration only and without anyintention of being limiting).

After a first time-temperature segment, preferably a short one, analuminum layer that is unprotected by the barrier layer is etched away,revealing all the layers that are protected by a barrier (X2 and V2 inFIG. 20). After a second time-temperature segment the aluminum layer ofthe TTI label that is covered by the barrier is etched away, revealing ahomogeneous yellow background, signaling that the end of the pre-settime-temperature of the label and good to which it is calibrated andthermally coupled (X3 and V3 in FIG. 20). It should be noted thatdifferent barrier materials as well as different barrier thicknesses maybe used in this embodiment, instilling the label with differentlifespans as well as temperature sensitivities (activation energy) forthe second time-temperature segment. It should further be noted that thelabel may be printed with one barrier layer or with a plurality ofbarrier layers providing segments that disappear one after the other,signaling the consumption of the pre-set time-temperature of the TTIlabel. It should be further noted that combinations of differentbarriers as well as different thicknesses may also be used in thisembodiment. The barrier layer may be colorless or colored, preferablybut not necessarily in the color of the revealing background.

It should be noted that the printing process described above may beperformed in other sequences, for example, printing the front of thelabel first then inverting the web and printing the back. Alternatively,a colored metalized polymer may be used, avoiding the need to print atthe back.

Optionally, any TTI of the above examples may be adapted to form an HTTIdevice, which measures elapsed time-temperature only above a pre-settemperature threshold, or an LTTI device, which measures elapsedtime-temperature only below a pre-set temperature threshold,

Threshold Indicators

As previously described, threshold indicators provide an indication ofexposure of the material or device (for example, optionally in the formof a label) to a temperature that is above a threshold temperature.However threshold indicators (TIs) may optionally be combined withfreeze indicators (FIs) and/or time-temperature indicators (TTIs). Somenon-limiting examples of TIs are described below.

FIG. 2 shows schematic illustrations of only the threshold indicatorcomponent alone according to various embodiments of the presentinvention. FIG. 2A shows a schematic view of a threshold indicator basedon crystalline dyes, in which FIG. 2A-1 shows the threshold indicatorbelow threshold temperature and FIG. 2A-2 shows the threshold indicatorabove threshold temperature.

FIG. 2B shows a schematic view of a threshold indicator based oncrystalline acid and acid-base indicator on paper, in which FIG. 2B-1shows the threshold indicator below threshold temperature and in whichFIG. 2B-2 shows the threshold indicator above threshold temperature.Non-limiting examples of materials for this embodiment includeanthocyanidines, methyl red, and the like.

In both cases, the colors shown are exemplary; it is simply desired thatthe threshold indicator changes from a first color state to a secondcolor state upon crossing the temperature threshold, in which the firstand second color states are different. A color state may optionally belack of color or a visible color, and/or development of or change in apattern of a plurality of colors. Examples of preparing the materialsfor both of these indicators are described with regard to Examples G andH.

FIG. 13 shows a non-limiting, illustrative example of a thresholdindicator based upon diffusion. A ˜100 micron layer of a mixture of acrystalline material having its melting-point at the desired activationtemperature of the TI and a dye is deposited on, or incorporated in, asubstrate 1. After the mixture crystallizes, a second layer 2 in theform of an opaque and absorbing fabric (nonwoven polymer, paper etc.) isplaced in direct contact with layer 1. These two layers are sandwichedin between two polymer layers. 3 and 6 using adhesive 7 that binds thetwo layers 3 and 6 all around layers 1 and 2.

Film 3 is optionally and preferably covered at its lower part with anadhesive 4 that enables the label to adhere to a surface, for exampleand without limitation, of a temperature sensitive good. The adhesive isprotected until activation with a release layer (liner) 5 that isnormally removed just before application of the label.

Layer 6 is optionally and preferably a transparent film printed withpictograms graphics, using opaque inks, leaving unprinted areas thatwill form the activation sign upon activation of the label. The film mayoptionally be translucent as long as the activation area remainsoptically available, for example visible. Upon activation (crossing thepre-set threshold temperature), the crystals in/on layer 1 melt, and themolten material dissolves the dye. The solution is being absorbed bylayer 2, thus coloring it with the dye. This layer becomes visual in thecolor of the dye through the openings in transparent film 6.

FIG. 14 shows an exemplary label having the layer structure of FIG. 13before (left) and after (right) activation (i.e. before and aftercrossing the threshold temperature).

FIG. 15 shows an exemplary, non-limiting illustrative thresholdindicator based upon metal etching. A ˜100 micron layer of a mixture ofa crystalline material having its melting-point at the desiredactivation temperature of the TI and an etchant, such as phosphorous orphosphoric acid, is deposited on an optionally colored substrate 1.Optionally, after the mixture crystallizes, a second layer 2 in the formof a colored and absorbing and optionally opaque fabric (nonwovenpolymer, paper etc.) is placed in direct contact with layer 1.Optionally and preferably, if layer 2 is not present, layer 1 itself(whether inherently or through an added composition on layer 1) and/oran optional layer below layer 1 (not shown) has some type of opticallyaccessible color, which may optionally be the visible light range. Forexample, a color forming agent may optionally be present in the etchingcomposition (etchant, crystals and dye) or in the carrier of thecomposition.

These two layers are sandwiched in between two polymer layers, layer 3(preferably comprising an opaque material, optionally aluminum) andlayer 6 (preferably comprising a metallic material which is morepreferably aluminum) using adhesive 7 that binds the two layers 3 and 6around layers 1 and 2. For example, layer 3 may optionally comprise apolymer film covered with aluminum, placed in contact with layer 4. Alsofor example, layer 6 may optionally comprise a transparent polymer filmcovered with aluminum, the aluminum layer being placed in contact withlayer 2.

In order to form the activation sign, one possibility is to print thesurface of the aluminum of layer 6 with an impervious barrier (notshown; a non-limiting example for such a layer is described in greaterdetail below), leaving as unprinted aluminum only the structure to berevealed. Film 3 is preferably covered at its lower part with anadhesive 4 that is used to adhere the label to surfaces. The adhesive isprotected until activation with a release layer (liner) 5 that isnormally removed just before application of the label.

FIG. 16 shows the threshold indicator of FIG. 15 in a schematic diagramof an exemplary label, in which a latent visual indication of expiry(that is, of a breach of a temperature threshold) appears uponactivation of the label (as shown in the label on the right; the labelon the left, before expiry, does not feature this visual indication).

Metal etching, such as aluminum etching as shown with regard to FIGS. 15and 16, has an advantage over diffusion based TI technologies. Diffusionbased TIs feature visual indications of the post-activation informationon the label even before activation (see the fleur-de-lis structure inFIG. 14). The only change upon activation is expressed in the color(changing from white to red upon activation). This is a disadvantage,especially when a clear cut “Yes/No” indication is needed for HACCP. Insuch cases, a label containing a latent sign that is being revealed uponactivation, such as in the case presented in FIG. 16, is clearlyadvantageous.

FIG. 17 shows a TI label having the layer structure of FIG. 15 (in thisexample without the impervious barrier) before and after activation.

Photonic Crystal Freeze Indicators

Freeze Indicators Based on Freezing of Water Water/Heavy Water Mixturesand Aqueous Solutions

The specific technologies described above related to thresholdindicators (s) which are employed to report temperature excursions toabove a pre-set temperature. These TIs are typically employed forreporting temperature excursions to pre-set temperatures above freezing,particularly for temperatures between 0 to 60 C. The FI technologiesdescribed below are employed to report temperature excursions that occurbelow a pre-set temperature; that is, exposure to a temperature that isbelow a minimum rather than above a maximum. These FIs are typicallyemployed for reporting temperature excursions to pre-set temperaturesabove, below or at freezing, particularly for temperatures between −10to +10 C.

Water is an anomalous solvent having its peak density at 4 C (H₂O) and11.6 (D₂O). FIG. 9 depicts the density of H₂O as a function of thetemperature. This anomalous phenomenon was used in the past for buildingfreeze indicators. The general concept was based on the fact that waterfreezes at 0 C and upon freezing expands by ˜9%. A sealed containercontaining water and a dye is placed on an absorbing medium. Uponfreezing, water breaks its container and the dye solution stains theabsorbing medium in a non-reversible manner.

More specifically, U.S. Pat. No. 4,191,125 to Johnson (“Johnson”)discloses a freeze indicator which includes a frangible ampoulesubstantially filled with a mixture of water, a nucleating agent, and asurfactant. Upon reaching the freezing point of water, the water mixturefreezes fracturing the frangible ampoule. According to Johnson anucleating agent can be used to overcome the undercooling effect; adye-printed pad can be employed to show a color change; and deuteriumoxide may be added to raise the freezing point.

Among the many drawbacks of the abovementioned technology is that itsembodiment is in the form of a macroscopic physical device that cannotbe produced using low-end and low-cost means. Consequently, the use ofsuch freeze indicators is rather limited. Surprisingly, the presentinventors have found that “photonic crystals”, a technology related tothe light effects of periodically arranged nanometer/micrometer spheres,offers a suitable solution to the goal of producing low-cost freezeindicator labels. Furthermore, optionally this solution obviates theneed for any macroscopic liquid container.

Such photonic crystals may also optionally be described as opalstructured crystals, which as described herein relate to an orderedstructure of object having same or similar size. According to at leastsome other embodiments of the present invention, there are also provided“inverse opal” structures, which are described in greater detail below.

Preparation of “opal” structures: The preparation of “opal” crystallineassemblies of colloids is reported in the literature (see for example a)N. P. Johnson, D. W. McComb, A. Richel, B. M. Treble, R. M. De La Rue,Synthetic Metals 2001, 116, 469-473. b) Y.-J. Lee, S. A. Pruzinsky, P.V. Braun, Langmuir 2004, 20, 3096-3106. c) S. Kubo, Z.-Z. Gu, H. Segawa,K. Takahashi, O. Sato, J. AM. CHEM. SOC. 2004, 126, 8314-8319. d) G. A.Umeda, W. C. Chueh. L. Noailles, S. M. Haile. B. S. Dunn, EnergyEnviron. Sci. 2008, 1, 484-486. e) O.D. Velev, E. W. Kaler, Adv. Mater.2000, 12, 531-534; all of which are hereby incorporated by reference asif fully set forth herein). Opal is composed of many tiny beads having asimilar size, arranged in a crystalline like manner. These referencesrelate to preparation of such structures from many nano/micron sizebeads.

The general approach to settling (gathering together in a usable format)nano-/micro-meter size beads is by applying a directional force to them,such as a flow of suspending solvent through a filter layer or gravity.This can be done either by using natural gravity or by using acentrifuge. Different materials, such as organic-polymer beads(polystyrene, latex, etc.), emulsion droplets, silica particles, etc.,may be used as nano/micro meter size beads. The crystalline structuremay be further derivatized by covering the surface with surfactants orpolymers or by slight sintering to render the structure stable.

Johnson et al describe a method for preparing opal structures thatfeature a crystalline structure as follows. Tetraethyl-o-silicate (TEOS)is first hydrolysed and subsequently condenses into silica spheres from“seeds” at a uniform temperature.

Preparation of “inverse opal” structures: The preparation of “inverseopal” (hereinafter denoting an ordered structure of pores having same orsimilar size inside a solid and/or semi-solid matrix) is reported in theliterature (see for example a) Y. Nishijima, K. Ueno, S. Juodkazis, V.Mizeikis, H. Misawa, M. Maeda, M. Minaki, OPTICS EXPRESS, 2008, 16,13676-13684. b) R. C. Schroden, M. Al-Daous, C. F. Blanford, Chem.Mater. 2002, 14, 3305-3315. c) Y-J Lee, P. V. Braun, Adv. Mater. 2003,15, 563-566; d) Stein et al, Chem Mater, 2008, 20, 649-666; e) Umeda etal, Energy Environ Sci. 2008. 1, 484-486; all of which are fullyincorporated by reference as if fully set forth herein).

The general approach to make “inverse opal” structures is based onimmersing “opal” structures inside a solution containing inorganicpolymer-forming monomers, such as tetramethoxy silane, (CH₃O)₄Si,zirconium acetate (Zr(OAc)₄), titanium isopropoxide (Ti(O-iso-propyl)₄)etc., and applying conditions under which said inorganic polymer-formingmonomers polymerize. The “opal” structure is then removed either bycalcination at high temperatures (in the case of organic nano/micrometer size beads) or by dissolution (for example, with HF solutions inthe case of silica beads), leaving the inorganic polymer outer shellwith cavities in place of the nano/micro meter size beads.

Lee et al describe inverse opal hydrogels, formed by using a mixture of2-hydroxyethylmethacrylate and acrylic acid as the building block forthe hydrogel. The precursor or “opal” structure was formed from apolystyrene latex suspension. After photopolymerization of the buildingblock in the template opal structure, the opal structure was removed bydissolution in chloroform.

Stein et al describe inverse opals made from ceria-zirconia materials.These materials are prepared by forming a nanoparticulate sol through areaction of zirconyl chloride and cerium ammonium nitrate, which is thenplaced in a template of polystyrene beads in suspension, followed byremoval of the beads by application of high temperatures. Thus, variouschemical and/or physical reactions are possible to remove the opaltemplate.

FIG. 28A shows an exemplary inverse opal photonic crystal, containing anaqueous solution. FIGS. 28B and 28C show an exemplary FI based upon thistechnology.

FIG. 28A shows an inverse opal photonic crystal containing water havinga green color originating from the order and size of the nanocontainers(inverse opal particles (the green color is shown in the circle toindicate how the crystal appears visually). Upon freezing, watershatters the nanocontainers, destroying the three dimensional order ofthe nanocontainers and associated color (as shown by the colored circle,representing the change in the visual appearance of the crystal).

As shown in FIG. 28C, the following layers are present: layer 1—releasetape (liner); layer 2—Adhesive; layer 3—Adhesive; layer 4—a compositioncontaining photonic crystals which may optionally be in the form of anink, a powder, a paste, a blister containing any of these and so forth;layer 5—a transparent or translucent polymer film; layer 6—(optionally)graphics, colors, pictograms and so forth and layer 7—base polymer film.In operation, the composition in layer 4 changes color (or, moretypically, loses color) upon freezing (or at least reduction of thetemperature below a low temperature threshold), thereby indicating thatthe low temperature threshold has been crossed. This change mayoptionally be determined optically and/or visually.

Unlike many other liquids, water expands in volume around the freezingpoint, such that upon freezing of water, the resultant volume ofcrystalline water is larger than the volume available in the container,resulting with the destruction of the container. The destruction of thecontainer serves as an indication of freezing. The liquid inside thecontainer may be died with a dye and the container placed on anabsorbing material. The color of the absorbing material may also serveas an indication of freezing.

A major drawback of this technology is that the indicator is a rigiddevice having a macroscopic volume of water enclosed in a fragilecontainer. This fact is associated with high costs, hazardous fragmentsof the container, macroscopic volumes of water, rigidity, large volumeetc. impeding the application of such devices. Freeze indictors (FIs)that are based on the freezing of water and aqueous solutions may alsobe made by encapsulating the solution in nano-containers having a narrowsize distribution and arranged in high order in two or three dimensions,forming a photonic crystal with the associated color properties.

Freeze indicators (FIs) according to the above description may generallybe made of a macroscopic sealed container as described in FIG. 33. Thedevice is composed of a container that contains dyed water or a dyedaqueous solution inside a container 1. The container 1 is usually placedon an absorbing fabric 2. In order to protect the system from anymechanical damage, the device is normally encased in a transparent andshock resistant case 3. Upon freezing, the volume of the frozen water islarger than the volume offered by the container, inducing itsdisintegration. Upon melting of the frozen water, the dye absorbs intothe absorbing fabric, thereby amplifying the freeze signal.

Inverse Viscosity/Inverse Freezing/Inverse Melting Freeze Indicators TTIand TI Devices Based on Inverse Freezing

Inverse freezing is a phenomenon in which a material, normally amixture, undergoes a liquid-to-solid transition upon heating. Thistransition is normally characterized by an abrupt increase of theviscosity of the system upon heating above a threshold temperature. Thisphenomenon may be applied to the production of very simple andinexpensive low-temperature threshold indicators, in a way that issimilar to the below described upper-temperature threshold indicators ofExamples G-I. FIG. 10 presents the viscosity of different mixtures ofalpha-cyclodextrin (alpha-CD), water and 4-methylpyridine (4MP) (molarratio provided in graph) as a function of the temperature. As can beclearly seen from the graph, at low temperatures the mixture is fluidwith a viscosity of ˜10-2 Pa s. Upon heating the viscosity does notchange significantly until approaching a threshold temp. Around thispoint the mixture exhibits a sharp increase in viscosity and practicallysolidifies. Upon cooling, this solid “melts” and returns to its fluidnature.

FIG. 18A shows an exemplary inverse freeze indicator (FI) label whileFIG. 18B shows this exemplary FI label in a schematic cross sectionaldiagram.

A ˜100 micron layer of an inverse melting mixture (shown as layer 4),optionally containing a dye, having its melting-point at the desiredactivation temperature of the FI, is deposited on a substrate 3.Optionally, after the mixture crystallizes, a film layer 5 in the formof a perforated and substantially non-absorbing, optionally opaque,polymer film is placed in direct contact with layer 4. An absorbing andoptionally opaque absorbing fabric 6 (nonwoven polymer, paper etc.) isplaced in direct contact with film layer 5. These three layers 4-5 aresandwiched in between two polymer layers, layer 3 (preferably comprisingan opaque material, optionally aluminum film, for example a polymerderivatized with or otherwise comprising aluminum) and layer 7(preferably comprising a transparent material) which allows visualinspection of the color of layer 6. The layers are preferably attachedby using adhesive 9 that binds the two layers 3 and 7 around layers 4, 5and 6. Layer 8 may be made by printing and contains written information,graphics, logos etc. This printed layer 8 does not necessary cover theentire area of layer 7, optionally leaving unprinted openings for theinspection of the color of layer 6.

Film layer 5 is preferably covered at its lower part with an adhesive 2that is used to adhere the label to surfaces. The adhesive is protecteduntil activation with a release layer (liner) 1 that is normally removedjust before application of the label.

FIG. 29 shows an exemplary technology for a FI based upon inversemelting. Yet another approach to produce FIs is based on the property ofsome materials and compositions to undergo inverse melting and/orinverse freezing and/or change their viscosity inversely to what mostmaterials do, meaning that their viscosity is, at least in onetemperature segment, proportional with the temperature (the viscosity ishigher at higher temperatures and lower at lower temperatures). Suchmaterials when cast in a certain shape, will retain their shape untilmelting (at, around or below a threshold low temperature) or until theviscosity drops to a sufficiently low value to allow fluidity (again,at, around or below a threshold low temperature).

FIG. 29 shows a very simple FI based on inverse melting/inverse freezingsystem enclosed in a vial. Steps 1-2 (heating the vial to above 30 Cuntil solidification of the material and then inverting the vial) areperformed in order to charge the FI. Upon reaching temperatures lowerthan 30 C, the red solid in the vial liquefies and drops to the bottomof the vial, following gravity.

Non-limiting examples of the preparation of such inverse-freezingindicators are shown in Example J.

Inverse TTI Devices—One early embodiment of time-temperature indicatorsincludes a porous medium and a colored viscous liquid penetrating intoit at a rate that is temperature dependent. The penetration rate isviscosity dependent and this in turn is temperature dependent, normallybeing low (fluid) at high temperatures and high (viscous fluid or solid)at low temperatures. Interestingly, using composition showing inversemelting one can device an inverse TTI that will “count” elapsedtime-temperature in an “inverse” manner, revealing the aggregatedtime-temperature excursions to lower temperatures. If the inversefreezing composition is characterized by a sharp transition in itsviscosity as a function of the temperature the TTI is a partial TTI andreports temperature excursions to temperatures below this transitionpoint.

Inverse melting and/or inverse freezing materials and/or materials thatchange their viscosity inversely to “normal” materials may also beharnessed to the production of inverse TTI systems, which are able toreport the summary of the inverse time temperature count (meaning thatthey will react more rapidly at lower temperatures and more slowly athigher temperatures). Optionally, such inverse TTI systems are partialTTI, providing the time-temperature history only below a pre-setthreshold temperature.

For such TTIs, the active material is optionally enclosed inside thecontainer and the device is inactive until seal is destroyed. Theviscosity of the active material is very high at above a pre-settemperature and the device is practically inactive (meaning that thetime-temperature count practically halts or is too low to have anypractical importance). Upon descending below the pre-set temperature theactive material of the device becomes less viscous and starts migratinginside the porous material, the migration distance providing a measureto the (inverse) time-temperature count. The device may be equipped witha scale providing information correlating the migration distance withtime at a given temperature or any other useful information.

FIGS. 30A and 30B show exemplary inverse TTIs based upon diffusion, incross section. As shown in FIGS. 30A1 and 30A2, which are schematicdiagrams of a cross-section of an exemplary inverse TTI based upondiffusion, a packaging 100 surrounds a porous medium 101 which isseparated from an inverse melting material in a container 103 by adestroyable seal 102 (FIG. 30A1). FIG. 30A2 shows an inspection window104; the inverse melting material from container 103 enters porousmedium 101 once destroyable seal 102 is destroyed, thereby providing anoptical indication (such as a visual indication for example) of the timetemperature history.

FIG. 30B shows the inverse TTI of FIG. 30A before activation (0), afteractivation (1) and after being exposed to increasing time-temperaturedoses (2)-(5).

Non-limiting examples of such devices are shown in Example M.

Optionally, any of the above TTI, FI and/or TI devices may be combinedin any manner, for example optionally in a single label or even a singledevice.

Optional Light to Dark TTI

The aluminum etching TTI technology described in the above examples istypically characterized by the transition from metallic shine through adark layer to the background color (mostly a light color), placed behindthe aluminum layer. Some applications require that the color change ofthe TTI be from a light color to a dark color. Placing a dark colorbehind the aluminum layer considerably shorten its lifespan, making thissolution less desirable for certain applications. For example, as thealuminum starts to disintegrate, it first breaks into small islands thatappear black. If put atop a white or light color background the eye seesa superposition of black and light color (say, for white you see gray,starting from almost black just after the islands are formed and endingin white where all the aluminum is etched). If a dark color is used, sayblack, this appearance is not apparent. It is therefore desirable tohave the ability to construct a TTI that is based on metal etching thatprovides the elapsed time-temperature history from a light color to adark color.

For both art known TTIs and TTIs described herein, as the timetemperature history is determined by the device, a metal etching processoccurs, during which the metal layer progresses from a mirror-likelayer, through a perforated black layer, to a transparent layer. Basedon this aluminum etching process, the visual effect of the active spotof the TTI is from a dark color to a light color, such as, for exampleand without limitation, bright yellow.

The color change of the TTI described above mainly relies on acombination of light absorption by the black aluminum layer and areflection from the yellow layer printed under the aluminized layer. Asthe aluminum layer is being etched away, the contribution of itsabsorption is reduced, more light reaches the yellow layer and thus morelight is reflected from it.

However, sometimes it is desirable for the process ofindication/visualization to be reversed, such that the initial color ofthe TTI is a light color and as time elapses and temperature occurs, thecolor of the TTI becomes dark.

In the new “Light to Dark TTI” structure a light-diffusive etchant labelis used instead of the existing transparent one. This is achieved bycoating the same etchant composition as described above on alight-diffusing film with a specific haze value, say for exampleoptionally and without limitation in the range of 25-60% haze values,such that the CIE-Lab color scheme for the active spot has particularvalues.

FIGS. 31 A-D show schematic block diagrams of exemplary light to darkTTI devices according to at least some embodiments of the presentinvention. For each figure, a top layer I is the light-diffusing layerand remains constant during all transition phases. A middle layer II isthe aluminized film layer (that is, this layer comprises aluminum and apolymer as described above, although of course other materials could beused) and is etched during the transition phases, affecting lighttransmission and reflectance.

A bottom layer III is the printed color under the aluminum that isgradually revealed through light reflectance as the aluminum is etched.

FIG. 32A shows such an exemplary light to dark TTI device in a label,indicating the effects of elapsed time, showing an activated Light toDark TTI stored at 50° C. in various stages of transition.

FIG. 32B shows a graph of CIE-Lab color value of the active spot for anexemplary light to dark TTI device, in which the device has a black backcolor behind the aluminized film and a front hazy PET film as the toplayer. The color values are shown as a function of the time afteractivation (with the device being stored at 60 C).

By contrast, FIG. 32C shows a graph of CIE-Lab color value of the activespot for a TTI device that is “dark to light” as described above, inwhich the device a process yellow back color behind the aluminized filmand a clear (non hazy) PET film as the top layer, with the device beingsubjected to the same conditions and the graph showing the color valuesas a function of the time after activation.

Optional Impervious Barrier for FI, TI or TTI Devices

Optionally, an impervious barrier may optionally be added to any devicedescribed herein. The impervious barrier is preferably applied to suchdevices having an etched metallic layer, such as TTI devices describedherein. Such devices comprise an aluminum label (or layer) and anactivation label (or layer). The activation label contains an etchantthat etches aluminum at a rate that is temperature dependent. Thealuminum label normally contains active segments, in which the etchingprocess is translated into a visual effect reporting avisual/electrical/optical summary of the elapsed time-temperature. Thealuminum label also contains printed areas in the form of pictograms,written information and graphics. Upon placing the activation label atopthe aluminum label the etchant starts etching the aluminum layer of thebase label.

One side effect of this process is that the aluminum underneath theprinted areas is also etched. Although this process is significantlyretarded and slowed by the printed ink layer, the etching of thealuminum layer under the graphic represents a serious esthetic drawbackand therefore must be prevented.

For that purpose, optionally a protective, printable and UV curableimpervious barrier composition may be printed atop non-functional areasof the labels that are devoted to non-changing information, such aspictograms, logo and graphics.

The following is a non-limiting example of an impervious barriercomposition and the effect of printing it underneath non-functionalareas of the label.

Such an impervious barrier was designed according to the followingguidelines:

1) UV-curable ink.

2) Can be printed on the same machine and using the same technology(Flexography) as all other printed layers.3) Retards significantly the etching process of aluminum by theactivation label.In order to retard the etching process, and in view of the fact that theetchant is a polar system (water, phosphoric acid), very hydrophobicbuilding blocks and cross-linker were selected. A non-limiting examplethat was used to demonstrate the approach is having the followingcomposition:

IBOA (SR506D) 20% W/W SR368 30% W/W SR295 40% W/W Esacure KIP 100F 10%W/WThe chemical structures of these molecules are shown in FIG. 21. Thesemolecules may optionally be used for the production (for example, byflexography printing and UV curing) of a non-limiting, exemplary,illustrative impervious barrier for a TTI.

The impervious barrier indeed blocks all etching processes. Due tolimited adherence to the aluminum layer as well as to variouscommercially suitable primers, the impervious barrier is optionally andpreferably printed in between the ink layers, more preferably as thethird layer above the aluminum (primer, ink I, impervious barrier, inkII, and so forth).

FIG. 22 depicts labels with and without the impervious barrier atdifferent temperatures.

FIG. 23 depicts the CIE-Lab color values of the non-functional yellowpart of TTI labels as a function of the time after activation with andwithout impervious barrier printed under the non-functional areas of thelabels. CIE-Lab color values are a specific color scheme determined bythe International Commission on Illumination (abbreviated CIE for itsFrench name, Commission Internationale de l'Éclairage).

As can be clearly seen from the graph, the etching of the aluminum layermay be completely blocked by printing an impervious barrier having theabove mentioned composition atop it.

Top Coating for TTI Devices

Water imperviousness may optionally be improved by adding a top coatingto any TTI device as described herein. For example, optionally a topcoating of a PVDC layer may be added to TTI labels for improved waterresistance. In many cases, activated labels are used at refrigeratedtemperatures and come in contact with condensed humidity in the form ofwater drops. As the top PET layer is not a perfect barrier for water,this water condensation atop the label influences the time temperaturecount (label kinetics). In order to overcome this limitation the top PETlayer was coated with a water impermeable layer in the form of a twomicron thick PVDC (Polyvinylidene chloride) layer.

FIG. 24 depicts the kinetics of two TTI labels immersed in water at 4 C,of which one contains a top PVDC coating while the other does not. Ascan be clearly seen from the graph, labels bearing a PVDC layer arewater tolerant and retain their kinetics while the kinetics of uncoatedlabels are influenced from being immersed in water. Also presented inthe graph as a reference two labels, one coated with PVDC and the otheruncoated that were placed in an incubator having ˜50% relative humidity(RH).

Printing with Flexography

Optionally the above described barrier layer may also be produced bydeposition, for example by flexography printing, of polymers such as forexample alkali soluble polyacrylates, atop the aluminum. For example, aTTI label as previously described, with a layer comprising aluminum, mayoptionally have an alkali soluble polyacrylate polymer printed atop theactive aluminum spot by means of flexography.

FIG. 34 shows the optical density as a function of the time afteractivation of an aluminized TTI label having an alkali solublepolyacrylate polymer printed atop the active aluminum spot by means offlexography. Specifically, the label has no back printing and thealuminized film is transparent. The labels were stored at a constanttemperature of 25 C.

Various embodiments and aspects of the present invention as delineatedhereinabove and as claimed in the claims section below find experimentalsupport in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions, illustrate some embodiments of the invention in anon-limiting fashion. The first set of Examples (Examples A, B, etc)describe various non-limiting examples of optional technologies whichmay be used. The second set of Examples (Examples 1, 2 etc) describesvarious business applications of time and/or temperature sensitivedevices.

Example A: Freeze Indicator Made of Ordered “Opal” Nanospheres Immersedin Water

Mono-dispersed nanometer-sized poly(methyl methacrylate) (PMMA) beadsprepared according to a literature known procedure (see for example Y.Xia, B. Gates, Y. Yin, Y. Lu, Adv. Mater. 2000, 12, 693-713 (andreferences therein), were closely packed by filtration through a filterpaper followed by careful slow drying. The ordered bead structurespellets were crushed into powder and immersed in water, avoidingdestruction of the close packing order of the beads. The colored powder(color depending on particle size) was then packed inside a thin PMMAcoating. Upon freezing, the crystalline structure of the “opal” isdestroyed irreversibly and the colored matrix turns white.

Example B: Freeze Indicator Made of Ordered “Inverse Opal”Nanocontainers Containing Water

Mono-dispersed nanometer-sized poly(methyl methacrylate) (PMMA) beads,prepared according to a literature known procedure (R. C. Schroden, M.Al-Daous, C. F. Blanford, Chem. Mater. 2002, 14, 3305-3315), wereclosely packed by filtration through a filter paper followed by carefulslow drying. The ordered bead structures pellets were crushed intopowder. The powder was then added to a solution of methanol (6.0 mL) andzirconium acetate (solution in dilute acetic acid in ethanol, 6.0 mL).The mixture was allowed to solidify and was further dried in a lowtemperature oven (60-80 C). Zirconium acetate was converted to zirconiaby calcination under air. The same process also removed the PMMAtemplate. The calcination point was reached by heating the sample at arate of 2 C/min up to 300 C. The sample was kept at 300 C for 2 h. andthen the temperature was increased again at a rate of 2 C/min untilreaching 450 C. The sample was kept at 450 C for 2 h, and then decreasedto ambient temperature at a rate of 5 C/min. The resulting solid wasthen pulverized, resulting with an “inverse opal” powder having a brightcolor that depends on the PMMA particle size. The “inverse opal” powderwas then immersed in water for several hours, then sealed by enclosingit in a thin PMMA coating.

Upon freezing, the crystalline structure of the “opal” is destroyedirreversibly and the colored matrix turns white, as demonstrated by testresults.

Controlling the Freeze Temperature

The temperatures at which aqueous solutions freeze are stronglydependent on the content of the solution. For example, added salts causethe solution to freeze at temperatures that are lower than zero Celsius.FIGS. 11 and 12 depict the effect of added NaCl to the freezing point ofwater.

It is more difficult to induce freezing of water at temperatures thatare higher than zero Celsius. Nevertheless, this can be achieved bymixing water with its isotopologues (HOD and D₂O for any practical use,in which one or more hydrogen atoms are replaced with deuterium). Whilepure H₂O freezes at 0 C, pure D₂O is reported to freeze at +3.8 C,providing the ability to induce freezing and associated volume expansionat temperatures above the normal freezing point.

Example C: Freeze Indicator Made of Ordered “Inverse Opal”Nanocontainers Containing a Mixture of H₇O with D₂O

A freeze indicator made according to example A was prepared using D₂O.The freezing temperature of D₂O is +3.8 C while the freezing temperatureof H₂O is 0 C. Thus, any freezing temperature in between the two bordertemperatures may be achieved simply by mixing the two waterisotopologues.

Example D: Freeze Indicator Made of Ordered “Opal” NanocontainersImmersed in a Mixture of H₂O with D₂O

A freeze indicator made according to example B was prepared using D₂O.The freezing temperature of D₂O is +3.8 C while the freezing temperatureof H₂O is 0 C. thus, any freezing temperature in between the two bordertemperatures may be achieved simply by mixing the two waterisotopologues.

Example E: Freeze Indicator Made of Ordered “Inverse Opal”Nanocontainers Containing a Mixture of H₂O with NaCl

A freeze indicator made according to example B was prepared using H₂O.The freezing temperature of is 0 C while adding salts such as NaCl, KC,CaCl₂ etc. reduces the freezing point of the solution. Thus, anyfreezing temperature in between at least 0 C and −20 C may be achievedsimply by mixing salts with water.

Example F: Freeze Indicator Made of Ordered “Opal” NanocontainersContaining a Mixture of H₂O with NaCl

A freeze indicator made according to example A was prepared using H₂O.The freezing temperature of is 0 C while adding salts such as NaCl, KCl,CaCl₂ etc. reduce the freezing point of the solution. Thus, any freezingtemperature in between at least 0 C and −20 C may be achieved simply bymixing salts with water, and/or optionally by mixing water with anorganic solvent such as ethanol, methanol, isopropanol or acetone;combinations of these approaches are also possible. The results ofmixing various salts with water are shown in FIG. 11, while the resultsof mixing the organic solvent methanol or the salt sodium chloride withwater are shown in FIG. 12.

Example G: Threshold Indicator—Lauric Acid

1 gr of lauric acid in the form of fine crystals was suspended in watercontaining 0.1 gr poly (ethyleneoxide) using vigorous stirring. Thesolution was filtered using a absorbing medium loaded with a congo-redacid indicator absorbed to it.

The absorbing medium was adhered to the surface of a label with the acidcrystalline powder facing the label and the clear side of the absorbingmedium facing the viewer.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 22 C, while inspecting the color of the absorbingmedium. The color of the absorbing medium was unchanged (slightyellowish color) until a temperature of 44 C was reached. At this point,the absorbing medium develops red spots in points where the crystals ofthe lauric acid melted. The absorbing medium turned full red within10-20 sec, depending on the loading of the crystals on the absorbingmedium.

Example H: Threshold Indicator—4′-Amino-N-Methylacetanilide

1 gr of 4′-Amino-N-methylacetanilide, in the form of fine crystals, wassuspended in water containing 0.1 gr poly (ethyleneoxide) using vigorousstirring. The solution was filtered using a filter-paper loaded with aphenol red base indicator absorbed to it.

The filter-paper was adhered to the surface of a label with the acidcrystalline powder facing the label and the clear side of thefilter-paper facing the viewer.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 22 C, while inspecting the color of thefilter-paper. The color of the filter-paper was unchanged (slightyellowish color) till reaching 70 C. At this point, the filter-paperdeveloped red spots in points where the crystals of the4′-Amino-N-methylacetanilide melted. The filter-paper turned full redwithin 10-20 sec, depending on the loading of the crystals on thefilter-paper.

Example I: Threshold Indicator Based on Melting of Dye Crystals

Example I-1: 0.1 gr of E-azobenzene (formula given below) in the form offine crystals was suspended in water containing 0.01 gr poly(ethyleneoxide) using vigorous stirring. The solution was filtered usinga filter-paper.

(E)-diphenyldiazene, (E)-Azobenzene

The filter-paper was adhered to the surface of a label with thecrystalline powder facing the label and the clear white side of thefilter-paper facing the spectator.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 22 C, while inspecting the color of thefilter-paper. The color of the filter-paper was unchanged (white) untilthe temperature of 69 C was reached. At this point, the filter-paperdevelops yellow-orange spots in points where the crystals of theE-azobenzene melted. The filter-paper turned fully yellow-orange within10-20 sec, depending on the loading of the crystals on the filter-paper.

Example I-2: 0.1 gr of N,N-diethyl-4-[(E)-phenylazo]aniline in the formof fine crystals was suspended in water containing 0.01 gr poly(ethyleneoxide) using vigorous stirring. The solution was filtered usinga filter-paper.

N,N-diethyl-4-[(E)-phenylazo]aniline

The filter-paper was adhered to the surface of a label with thecrystalline powder facing the label and the clear white side of thefilter-paper facing the spectator.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 22 C, while inspecting the color of thefilter-paper. The color of the filter-paper was unchanged (white) untilthe temperature of 95 C was reached. At this point, the filter-paperdevelops yellow-orange spots in points where the crystals of theN,N-diethyl-4-[(E)-phenylazo]aniline melted. The filter-paper turnedfully yellow-orange within 10-20 see, depending on the loading of thecrystals on the filter-paper.

Example J: Low-Temperature Freeze Indicators Based on Materials ShowingInverse Freezing

Example J-1 one label system: A mixture of 1:6:40 α-cyclodextrin (α-CD),water and 4-methylpyridine (4MP) was stirred at 15 C until homogeneous.Small amount (˜1×10⁴ M) of erythrosine B was added to the solution inorder to render it red. The mixture was spread on a polymer film andwarmed to 50 C for solidification. The solidified material was coveredwith a porous non absorbing film. Filter-paper or non-wovenpolypropylene fabric was then used to cover the spread in a way thathinders the spread from the eye. The indictor was left to cool down at arate of ˜0.1-0.2 C/min. upon cooling no change is observes in theappearance of the filter-paper until temperature reached 37 C. At thistemperature the spread turns liquid and wets the filter-paper, thuscoloring it reddish. The coloration process is completed within seconds.

Example J-2 two label system: A mixture of 1:6:40 α-cyclodextrin (α-CD),water and 4-methylpyridine (4MP) was stirred at 15 C until homogeneous.Small amount (˜1×10⁻⁴ M) of erythrosine B was added to the solution inorder to render it red. The mixture was spread on a polymer film andwarmed to 50 C for solidification. The solidified material was coveredwith a porous non absorbing film and this was then covered with asiliconized protective layer. This part of the indicator is inactive asit lacks an absorbing medium that its coloration with the dyed fluiddenotes temperature abuse. Activation of the indicator is performed byremoving the siliconized protective layer and uncovering the solidmixture spread, and then covering it with a filter-paper or anotherabsorbing layer such as non-woven polypropylene layer. The indictor wasleft to cool down at a rate of ˜0.1-0.2 C/min. upon cooling no change isobserves in the appearance of the filter-paper until temperature reached37 C. At this temperature the spread turns liquid and wets thefilter-paper, thus coloring it reddish. The coloration process iscompleted within seconds.

Example K—Combined High and Low Temp. Threshold Indicators

Example K-1 one label system: A mixture of 1:6:40 α-cyclodextrin (α-CD),water and 4-methylpyridine (4MP) was stirred at 15 C until homogeneous.A small amount (˜1×10⁻⁴ M) of erythrosine B was added to the solution inorder to render it red; this substance is optional and may be omitted.The mixture was spread on a polymer film in the form of a circle, warmedto 50 C for solidification.

0.1 gr of 4′-Amino-N-methylacetanilide, in the form of fine crystals,was suspended in water containing 0.01 gr poly (ethyleneoxide) usingvigorous stirring. The suspend powder was filtered, dried and placed onthe same polymer film bearing the α-cyclodextrin (α-CD), water and4-methylpyridine (4MP) spread and the system was covered with a porousfilm.

A phenol red base indicator was absorbed to a filter-paper and thefilter-paper was dried. The filter-paper was then adhered to the surfaceof a polymer film bearing the crystals and spread in a way thefilter-paper hinder them from the spectator.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 50 C, while inspecting the color of thefilter-paper. The color of the filter-paper was unchanged (slightyellowish color) till reaching 70 C. At this point, the filter-paperdevelops red spots in points where the crystals of the4′-Amino-N-methylacetanilide melted. The filter-paper turned full redwithin 10-20 sec, depending on the loading of the crystals on thefilter-paper. A similar label at 50 C was left to cool down at a rate of˜0.1-0.2 C/min. Upon cooling no change is observes in the appearance ofthe filter-paper until temperature reached 37 C. At this temperature thespread turns liquid and wets the filter-paper, thus coloring it reddish.The coloration process is completed within seconds.

Example K-2 two label system: A mixture of 1:6:40 α-cyclodextrin (α-CD),water and 4-methylpyridine (4MP) was stirred at 15 C until homogeneous.A small amount (˜1×10⁻⁴ M) of erythrosine B was added to the solution inorder to render it red; as previously described, this substance isoptional. The mixture was spread on a polymer film in the form of acircle and warmed to 50 C for solidification.

0.1 gr of 4′-Amino-N-methylacetanilide, in the form of fine crystals,was suspended in water containing 0.01 gr poly (ethyleneoxide) usingvigorous stirring. The suspend powder was filtered, dried and placed onthe same polymer film bearing the α-cyclodextrin (α-CD), water and4-methylpyridine (4MP) spread, and the system was covered with a porousfilm, then covered with a siliconized protective layer. This part of theindicator is inactive as it lacks an absorbing medium that itscoloration with the dyed fluid denotes temperature abuse. A phenol redbase indicator was absorbed to a filter-paper and the filter-paper wasdried.

Activation of the label was done by adhering the filter-paper to thesurface of the polymer film bearing the crystals and spread in a waythat the filter-paper shields them from the spectator.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 50 C, while inspecting the color of thefilter-paper. The color of the filter-paper was unchanged (slightyellowish color) till reaching 70 C. At this point, the filter-paperdevelops red spots in points where the crystals of the4′-Amino-N-methylacetanilide melted. The filter-paper turned full redwithin 10-20 sec, depending on the loading of the crystals on thefilter-paper. A similar label at 50 C was left to cool down at a rate of˜0.1-0.2 C/min. Upon cooling no change is observes in the appearance ofthe filter-paper until temperature reached 37 C. At this temperature thespread turns liquid and wets the filter-paper, thus coloring it reddish.The coloration process is completed within seconds.

Example L: Combined Electrical Threshold-Freeze Indicator

As can be clearly appreciated from the above examples, the TI or TTIdevice may optionally be constructed separately in the form ofelectrical threshold indicator as well as electrical freeze indicator.It should also be noted that any of the abovementioned thresholdindicating examples may be put in between electrodes and be read alsothrough reading any electrical property that changes as a function ofthe changes to the device that are caused by crossing threshold/freezelimits. A non-limiting example is provided below of a one-label combinedTTI device.

A mixture of 1:6:40 alpha-cyclodextrin (alpha-CD), water and4-methylpyridine (4MP) was stirred at 15 C until homogeneous. A smallamount (˜1×10⁴ M) of erythrosine B was added to the solution in order torender it red; as previously described, this substance is optional. Themixture was placed at a small part at the end of an absorbingmedium(filter paper, non-woven polypropylene, glass beads oralike)adhered atop an electrically conductive electrode surface andwarmed to 50 C for solidification.

0.1 gr of 4′-Amino-N-methylacetanilide, in the form of fine crystals,was suspended in water containing 0.01 gr poly (ethyleneoxide) usingvigorous stirring. The suspended powder was filtered, dried, mixed witha very small amount of crystals of a red color pigment and placed at asmall part at the end of a second absorbing medium adhered atop the sameelectrically conductive electrode surface and dried. Both filter-paperswere then covered with a second electrode (may be also a transparentelectrode).

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 50 C, while inspecting the color of the absorbingmedium. The color of the filter-paper was unchanged (white) tillreaching 70 C. At this point, the absorbing medium bearing the crystalsof 4′-Amino-N-methylacetanilide starts wetting in red where the crystalsof the 4′-Amino-N-methylacetanilide melted and dissolved the crystals ofthe red pigment. The red wet part of the absorbing medium graduallyexpands until it reaches its end and the absorbing medium is completelyred. The red color progresses at a rate that is temperature dependent,faster at elevated temperatures. At temperatures around the freezingpoint of 4′-Amino-N-methylacetanilide and below it the progression ofthe red color is practically halted. The capacitance and resistance ofthe system changes as the red color progresses inside the absorbingmedium. This allows reading of the excursions above the thresholdtemperature using any electronic device that is capable of readingcapacitance and/or resistance.

A similar label at 50 C was left to cool down at a rate of ˜0.1-0.2C/min. Upon cooling no change is observes in the appearance of theabsorbing medium until temperature reached 37 C. At this temperature thespread turns liquid and wets the absorbing medium, thus coloring itreddish. At this point, the absorbing medium starts wetting in red wherethe solid composition became fluid. The red wet part of the absorbingmedium gradually expands until it reaches its end and the absorbingmedium is completely red. The red color progresses at a rate that istemperature dependent, slower at elevated temperatures. At temperaturesaround the freezing point of mixture and above it the progression of thered color is practically halted. The capacitance and resistance of thesystem changes as the red color progresses inside the absorbing medium.This allows reading of the excursions above the threshold temperatureusing any electronic device that is capable of reading capacitanceand/or resistance.

Example M—Inverse TTI Devices

Example M-1 one label system: A mixture of 1:6:40 alpha-cyclodextrin(alpha-CD), water and 4-methylpyridine (4MP) was stirred at 15 C untilhomogeneous. A small amount (˜1×10⁻⁴ M) of erythrosine B was added tothe solution in order to render it red. The mixture was warmed to 50 Cfor solidification and then spread atop the end of an absorbing mediumstrip that was adhered to a polymer film in a way it covers only a smallportion of the absorbing medium strip and in places it covers the stripit is spread homogeneously across it. The part of the absorbing mediumthat is covered with the mixture was then covered with an opaque polymerfilm in a way the absorbing medium hinder them from the spectator.

The label was then put on a heating plate at 70 C and was left to cooldown at a rate of ˜0.1-0.2 C/min. Upon cooling no change was observed inthe appearance of the absorbing medium strip until temperature reached˜37 C. At this temperature the spread turns liquid and wets theabsorbing medium strip, thus coloring it reddish. The colored fluidfront progresses along the absorbing medium strip at a rate that isinversely temperature dependent so that upon cooling it accelerates andupon heating it slows down and even stops migrating.

Similar embodiments may include a sealed container containing the spreadand that inverse TTI activated by pressure or by puncturing thecontainer or by creating openings in it in any way known in the art. Yetanother embodiment may include a container residing on an inert support,say a polymer film, with another label containing the porous paper stripin a way that only combining the two initiates the time-temperaturecount.

Example M-2 two label system: A mixture of 1:6:40 alpha-cyclodextrin(alpha-CD), water and 4-methylpyridine (4MP) was stirred at 15 C untilhomogeneous. A small amount (˜1×10⁻⁴ M) of erythrosine B was added tothe solution in order to render it red; this substance is optional aspreviously described. The mixture was spread on a polymer film in theform of a circle and warmed to 50 C for solidification.

0.1 gr of 4′-Amino-N-methylacetanilide, in the form of fine crystals,was suspended in water containing 0.01 gr poly (ethyleneoxide) usingvigorous stirring. The suspended powder was filtered, dried and placedon the same polymer film bearing the alpha-cyclodextrin (alpha-CD),water and 4-methylpyridine (4MP) spread, then covered with a siliconizedprotective layer. This part of the indicator is inactive as it lacks anabsorbing medium that its coloration with the dyed fluid denotestemperature abuse. A phenol red base indicator was absorbed to anabsorbing medium and the absorbing medium was dried.

Activation of the label was done by adhering the filter-paper to thesurface of the polymer film bearing the crystals and spread in a way theabsorbing medium hinder them from the spectator.

The label was then put on a heating plate and heated gradually (˜0.5C/min), starting from 50 C, while inspecting the color of the absorbingmedium. The color of the absorbing medium was unchanged (slightyellowish color) till reaching 70 C. At this point, the absorbing mediumdevelops red spots in points where the crystals of the4′-Amino-N-methylacetanilide melted. The absorbing medium turned fullred within 10-20 sec, depending on the loading of the crystals on theabsorbing medium. A similar label at 50 C was left to cool down at arate of ˜0.1-0.2 C/min. Upon cooling no change is observes in theappearance of the absorbing medium until temperature reached 310K. Atthis temperature the spread turns liquid and wets the absorbing medium,thus coloring it reddish. The coloration process is completed withinseconds.

Example N—Out of Standard Temperature TTI Devices

As can be appreciated from the various examples of TTI devices given inExample M, one can easily combine known normal TTI (for example, theabovementioned metal based TTI or a diffusion based TTI known in theart) with inverse TTIs (for example, two TTI located side by side,experiencing the same temperature at any given time).

This type of indicator will provide a visual indication of the historyof the product to which it is thermally coupled, indicating thetime-temperature it experienced outside set temperature boundaries.

Example O—Freeze Indicator

Materials:

α-CD=α-cyclodextrin

2-MP=2-Methyl pyridine=2-Picoline

4-MP=4-Methyl pyridine=4-Picoline

Preparation of Samples:

X-MP and water were added to α-CD in a glass vial at low temperature andstirred until all the cyclodextrin was dissolved.

Results are shown in FIG. 25. As can be seen from the figure, all thecompositions are solid at 50 C. At 23 C some of the compositions liquefywhile others remain solid. Most compositions are liquid at 0 C while allof them are liquids at −23 C. As can be seen from FIG. 25, one can tunethe liquefaction of the medium simply by selecting the members of thecomposition and their ratio.

Example P—Tests of Threshold-60 V1 Label

This label is a TTI prepared according to the above examples. Itsstructure is shown in FIG. 26.

The active medium used in this label was characterized by DSC(Differential Scanning Calorimetry). The melting temperature of themixture of Myristic acid and Erythrosine B was determined.

Experiment conditions: Melting points were recorded on a PL-DSC (PolymerLaboratories) machine. Calibration of the machine was performed on anIndium standard (mp=156.6° C.). 13.2 mgr of the Myristic acid andErythrosine B mixture (˜2% w/w dye in the acid) were melted and cooledto room temperature, allowing re-crystallization. The mixture was loadedinto a metallic capsule and DSC was run at a rate of 0.1 C/min. Theobserved melting temperature of the mixture is around 55 C The resultsare presented in FIG. 27.

Next, 16-20 labels were incubated at three controlled temperatures (25°C., 37° C., 50° C.). The labels were photographed every few days withthe aim to verify if they activate after incubation at the testtemperatures (results not shown). The labels stored at 25° C., 37° C.and 50° C. were not activated for at least 161 days. The surface of thelabels stored at 50° C. became wavy, probably because of somedeterioration of the polypropylene material and/or ink used forprinting. All labels tested were activated when placed at temperaturesabove the threshold temperature.

Next, four Threshold-60 V1 labels were placed on glass plates andimmersed in water baths at 37° C. and 50° C. The labels stored, immersedin water, at 37° C. were stable for at least 109 days. They were notdamaged nor activated at any time during storage. The labels remainedactive and could be activated by heating them to temperatures above thethreshold temperature. The labels stored, immersed in water, at 50° C.were destroyed after about 60 days. The upper PP film of the label wasdestroyed and water penetrated the label interior. The dyestuff waswashed out of the labels and the labels lost their ability to beactivated. Thus the labels can withstand some immersion in water.

Business Examples

The next set of Examples (Examples 1-4) describes various non-limiting,exemplary business applications of time and/or temperature sensitivedevices. Such Examples may optionally be implemented with any of theabove described technologies.

Example 1—Promotional Object

According to at least some embodiments, there is provided a promotionalobject, which is a time and/or temperature sensitive device having adisplay that features a coupon or other incentive to stimulate apurchase and/or a visit to a commercial location. Non-limiting examplesof such a commercial location include a store, a restaurant, a movietheatre, a live performance location, a club and the like. The displaymay optionally feature the incentive in a single appearance after a settime or with a multi stage appearance, in which the display changes aplurality of times to feature the incentive(s).

The promotional object may optionally take a two dimensional or threedimensional shape. Non-limiting examples of such an object include alabel and a card. The promotional object features a display that iscapable of displaying a single sign or a plurality of signs. Accordingto at least some embodiments, however, optionally the sign or at leastpart of the sign is initially concealed upon provision of thepromotional object to the user. In other words, optionally the recipient(user) does not initially see the entirety or all of the concealed signor signs of the display. The user may optionally see other sign orsigns, which may optionally be pre-printed on the object, for example toindicate that the display will change at a later time.

Alternatively, according to at least some embodiments, a single sign orplurality of signs may optionally be displayed, for example from receiptof the promotional object by the user, and then gradually disappear.

Optionally, the latent sign may optionally bring its holder a benefitonly if the same sign or a complementary sign is present on the objectin its non-latent parts (that is, in a part of the object that isimmediately visible to the user). Alternatively, the object mayoptionally contain a plurality of signs that are latent at the time thecoupon is issued and are revealed at a rate that is temperaturedependent or at a rate that is time and temperature dependent in a waythat they form different combinations that lead to different benefits atdifferent time intervals after activation of the object.

As previously described, even if the promotional object comprises bothtime and temperature sensitive elements, the user may optionallyperceive the time sensitive element only, given that the display changesafter at least some time has elapsed. Optionally and alternatively, thepromotional object may feature only temperature sensitive elements,requiring application of heat and/or cold for the display to change.

Optionally, different promotional objects may feature different signs,indicating different benefits, or alternatively they may feature thesame sign, indicating the same benefit. Optionally, only somepromotional objects feature a sign or signs indicating a benefit.

The promotional object may optionally be printed with the desired textand/or graphic design, optionally and preferably including the logo andbrand name of the issuing body. The display of the promotional objectpreferably comprises an active area, which can be separate from theprinted information or be entirely or partially integrated with it.Depending upon the time and/or temperature sensitive technology used toimplement the active area, the active area may optionally comprise aplurality of layers. For example, the active area may optionallycomprise a metal layer (a non-limiting example of which is aluminum) anda second layer that contains an etchant that is capable of etching themetal layer at a rate that is temperature dependent or at a rate that istime and temperature dependent.

As the etching process is dynamic, at different time intervals afteractivation, the coupon offer different benefits to its holder. Forexample, such an implementation may optionally be used for an objectwhich contains a plurality of signs that are latent at the time thecoupon is issued and are revealed at a rate that is temperaturedependent or at a rate that is time and temperature dependent in a waythat they form different combinations that lead to different benefits.

Without wishing to be limited by a single implementation or a closedlist, the at least time lapsed nature of the display, such that the userneeds to wait for at least a certain period of time before using thepromotional object, enables the issuing entity to ensure that the usercannot use the object before a certain period of time has elapsed. Forexample and without limitation, if the promotional object included anincentive issued by a store, the user would be required to return to thestore (optionally a different branch of the same store) to use theincentive displayed on the object.

A non-limiting, exemplary detailed implementation of such a promotionalobject is shown in FIG. 35 below. For all of the figures described inExample 1, although a certain number of layers is described, optionallyany number of layers may be used.

FIG. 35A depicts schematic top and cross section views of a non-limitingexample of a promotional object before activation. Before activation,the object optionally comprises two separate systems, a base label 100and an activation label 101.

Base label (100) optionally and preferably comprises a polymer film(106) bearing a thin metal layer 105, such as for example, aluminum.Metal layer 105 may be partially covered with colors, pictograms andwriting such as logo and information (104), leaving at least one part ofthe metal layer 105 as an uncoated layer (102). Covered layer (104) maybe composed of a single layer of paint or lacquer or polymer.Alternatively, covered layer (104) may contain a plurality of layers ofpaints and or lacquers and or polymer layers. The polymer film (106) maybe printed on its non-aluminized surface (107) with information, such asfor example the check or “/” shape, which remains latent until etchingof the aluminum layer had advanced. The polymer film (106) mayoptionally be further printed and coated with additional layersproviding additional latent information, background color etc. (108).Layer (108) optionally comprises a single layer of paint or lacquer orpolymer. Alternatively, layer (108) may contain a plurality of layers ofpaints and or lacquers and or polymer layers. Base label 100 mayoptionally further comprise and additional layer (109) which comprisesan adhesive and a liner material.

Activation label (101) optionally comprises a transparent orsemi-transparent, usually colorless polymer layer (110) that bears athin layer of the metal etching component inside a pressure sensitiveadhesive (111).

As a non-limiting example, activation of an object 103 is optionallyperformed by adhering activation label (101) to the uncoated metalsegment (102) of base label (100). The freshly activated object 103bears a shiny metal surface (102).

FIGS. 35B-D1 show object 103 with metal layer 105 that is graduallybeing etched by the metal etching component inside a pressure sensitiveadhesive (111). FIG. 35B shows object 103 just after activation. As themetal layer is etched, the latent signal (107) is revealed gradually, asshown in FIGS. 35C and 35D. For comparison, FIG. 35C-1 and FIG. 35D-1present an object 105 in which the check sign was not printed at thestages that are equivalent to FIG. 35C and FIG. 35D, respectively.

According to at least some embodiments, the promotional object mayoptionally comprise a sandwich label. For example, the activation labelmay optionally be attached to the base label in a way that is describedabove in FIG. 1C.

According to at least some embodiments, the promotional object mayoptionally comprise an impervious layer under a printed surface. Forexample, in order to solve the problem of the etchant label etching thealuminum under the printed regions, it is possible to use an imperviousbarrier layer, described above in FIG. 21 (presenting a non-limitingexample of a composition of monomers), FIG. 22 (presenting pictures oflabels fresh after activation and after 203 days at 37 C and 50 C) andFIG. 23 (presenting graphs of the yellow color of the labels of FIG. 22incubated at 37 C as a function of the time after activation).

According to at least some embodiments, the promotional object mayoptionally comprise a plurality of spots being revealed at differenttime intervals after activation. For example, FIGS. 6-8 above describethe formation of a plurality of aluminum spots having the same metallayer thickness that are being etched at different temperature dependentor time temperature dependent rates using different light transmissivepermeable barrier layers that are printed atop the aluminum layer andserve for altering the etching properties of the aluminum layer by theetchant layer. Such light transmissive permeable barrier layers may beused for creating objects in which the latent information concealedunder the aluminum spots are revealed at different time intervals afteractivation.

Different conditions may optionally apply to the materialization of theobject benefit such as giving the object owner the sum of the revealedbenefits or giving the object owner the sum of the revealed benefitswithin a set time limit or giving the object owner the last revealedbenefit or alike. For example, FIG. 36 depicts a multi spot promotionalobject according to at least some embodiments of the present invention,implemented according to the abovementioned technologies. Each of FIGS.36A-D show a promotional object 120 at different time intervals. FIG.36A shows object 120 before activation. FIG. 36B shows an initialincentive, in this case 50% off of the product shown in the left mostwindow, as the first display after activation. In FIG. 36C, after afurther lapse of at least time, another product is shown in the middlewindow. In FIG. 36D, after a further lapse of at least time, yet anotherproduct is shown in the right most window. The benefit grows with timeafter activation and the holder is motivated to keep the object andre-visit the store, restaurant or other issuing business location.

For yet another example, FIG. 37 shows a multi spot object madeaccording to the abovementioned technologies according to at least someembodiments at different time intervals after activation but with theprovision of only one incentive to the user. In this case, the benefitdoes not necessarily grow with time after activation and the user isrequired to decide when is the best time re-visiting the store andmaterializing the benefit.

According to at least some embodiments, the promotional object mayoptionally comprise a plurality of spots both appearing (being revealed)and disappearing at different time intervals after activation. FIGS. 6-8above teach the formation of light transmissive permeable barrier layersthat are printed atop the aluminum layer and serve for altering thetemporal and temperature dependent evolution of the etching of thealuminum layer by the etchant layer. Such light transmissive permeablebarrier layers may be used for creating objects in which the latentinformation it contains in the aluminum spots is revealed at differenttime intervals after activation then, at a later stage is erased. FIGS.38A-C shows an object according to at least some embodiments in which asingle spot reveals latent information after a certain time afteractivation and then after yet another time interval the revealedinformation fades and disappears. FIG. 39 presents a cross section of anon-limiting example of an object of FIGS. 38A-C.

Before activation, an object 103 preferably comprises two separatesystems, base label 101 and activation label 101 as shown in FIG. 39.

Base label (100) optionally and preferably is constructed as describedabove with regard to FIG. 35A. As previously described, metal layer 105preferably features an uncovered or uncoated part 102. The uncoveredpart 102 of the metal layer 105 is preferably printed with a lighttransmitting permeable barrier layer or layers (109) that is printedatop metal layer 105 and alters the etching properties of metal layer105 by the etchant layer of activation label 101 (see for example FIGS.6-8 above).

Activation label (101) is preferably prepared as described above, with atransparent or semi-transparent, optionally colorless polymer layer(110) that bears a thin layer of the metal etching component inside apressure sensitive adhesive (111).

Activation of object 103 is preferably performed by adhering activationlabel (101) to the uncoated metal segment (102) of base label (100). Thefreshly activated base label 100 bears a shiny metal surface (uncoatedpart 102) that is gradually being etched by the metal etching componentinside a pressure sensitive adhesive (111).

Just after activation uncoated part 102 may optionally appear reflectiveas shown in FIG. 38A. As uncoated part 102 of the metal layer is notfully covered by the permeable barrier layer 109, the uncoated parts ofthe aluminum are etched faster, revealing a metallic shape in the formof the printed permeable barrier layer 109, as shown in FIG. 38B. Afteran additional time interval the etchant layer of activation label 101penetrates the permeable barrier 109 and etches the aluminum layer ofuncoated metal part 102 underneath, causing the disappearance of theexposed signal, as shown in FIG. 38C.

FIGS. 40A-D depict a object in which a plurality of spots reveal latentinformation at different time intervals after activation and then afteryet additional time intervals the revealed information exposed in thedifferent spots they fade and disappear. Printing different permeablebarriers or the same permeable barrier but at a different thickness onthe different metallic parts allows the programming of the order andrate of disappearance of the revealed information. FIG. 41 shows theobject of FIG. 40 in cross-sectional detail.

Before activation, the object 103 of FIG. 41 optionally and preferablycomprises two separate systems: base label (100) and activation label101 as previously described. Base label 100 is optionally and preferablyconstructed as described with regard to FIG. 39; however preferably thebackground of at least two of the three aluminum spots (uncoated metalpart 102) is also covered with a permeable barrier layer 109 in order toallow the latent information concealed in each aluminum spot to berevealed at a different time after activation. If these layers (109) areprinted from different compositions or of the same composition but witha different thickness, the different permeable barriers 109 will presentdifferent protection against the etching process, resulting in differentlifetimes for etching of the same aluminum layer 105 under the differentpermeable barriers.

Activation label (101) is also preferably constructed as described withregard to FIG. 39.

Activation of the object 103 is performed by adhering activation label(101) to the uncoated metal segment (102) of base label (100). Thefreshly activated base label 100 bears shiny metal surfaces (102) thatare gradually being etched by the metal etching component insidepressure sensitive adhesive (111) of activation label 101. Just afteractivation uncoated metal segment (102) optionally and preferablyappears reflective as shown in FIG. 40A. As the metal layer 105 iscovered by different thicknesses of the permeable barrier layer 109, theparts of the metal layer 105 that are coated with the thinnest layer 109are etched first, revealing a metallic shape in the form of the thickerpermeable barrier layer 109 in the spot on the left as shown in FIG.40B. After an additional time interval the etchant layer penetrates thethinner permeable barrier layer 109 around the thicker permeable layer109 of the central spot, revealing the second concealed shape, shown inFIG. 40C. At this stage there are two exposed shapes. After yet anothertime interval, the shapes on the left and central spots are etched,leaving blank spots while the surrounding aluminum layer of the rightspot is etched, revealing the third shape, as shown in FIG. 40D. Thisshape will also disappear with time. The holder of the object mayoptionally select an incentive at any time, such that waiting for theprocess to end is no longer the best solution for maximizing profit.

The above embodiments may also optionally be further combined by anappearing signal relying on the use of an impervious barrier, asdescribed in greater detail below, as well as combinations of thisembodiment with the above embodiments. Also optionally, the promotionobject may be provided in a preactivated form, such that the time and/ortemperature sensitive clock has already started running and the timerequired for any of the above events to occur is already elapsing, alsodescribed in greater detail below.

In yet another embodiment the appearing latent signal is achievedthrough printing an impervious barrier atop the aluminum layer. As thislayer is impervious to the etchant, the unprinted surrounding areas ofthe aluminum layer are etched at a certain time after activation of thepromotional object while all the aluminum area that was printed with theimpervious barrier are not being etched at any time after activationthat is relevant to the purpose of the function of the promotionalobject.

FIGS. 42A, 42B and 42C show an exemplary promotional object in which asingle spot reveals latent information after a certain time afteractivation and the revealed information fades slowly or does not fade atany time that is relevant to the function of the promotional object. By“relevant to the function of the promotional object” it is meant thatthe display does not fade during the time period required for thepromotional object to display the latent information. FIG. 43 presents across section of a non-limiting example of a promotional object of FIG.42.

Before activation, the promotional object 103 comprises two separatesystems as previously described, a base label 100 (prepared as describedabove) and an activation label 101 (also prepared as described above).

An uncovered part (metal segment) 102 of the metal layer 105 isoptionally and preferably covered (for example by being printed,painted, sprayed, coated and so forth) with a light transmissiveimpervious barrier layer (109) that alters the etching properties of themetal layer 105 by the etchant layer of activation label 101 (see alsoFIGS. 6-8 above).

Activation of the promotional object 103 is performed by adheringactivation label (101) to the uncovered metal segment (102) of baselabel (100) that is partially covered by the impervious layer (109). Thefreshly activated base label 100 bears a shiny metal surface (102) aspart of metal layer 105. The portions of metal layer 105 that are notcovered by impervious layer 109 are gradually etched by the metaletching component inside a pressure sensitive adhesive (111).

Just after activation the metallic area 102 is reflective as shown inFIG. 42A. As the metal layer 105 is not fully covered by the imperviousbarrier layer (109), the uncoated parts of metal layer 105 are etchedwhile the covered parts are not etched, revealing a metallic shape inthe form of the printed permeable barrier layer (109), as shown in FIG.42B. The revealed form is preferably not etched by the etchant, andhence does not fade or is not destroyed, at any time that is relevant tothe function of the promotional object as shown in FIG. 42C.

For some applications of the present technology it is advantageous tohave some of the barrier layers (109) as permeable layers that retardthe etching process of metal layer 105, while other barrier layers 109are impervious layers that prevent etching of metal layer 105. In bothcases barrier layers 109 preferably are in contact with metal layer 105.The purpose of this embodiment is to increase the complexity of thedisplay of information of which the promotional object 103 is capable.

FIGS. 44A-D show a promotional object 103 in which information isrevealed in some spots and remains, while such information is revealedin other spots but disappears within a functionally relevant timeperiod. By “functionally relevant time period” it is meant that thedisplay changes during the time period required for the promotionalobject to remain functioning, for example to provide information to theuser through the visual display. FIG. 45 shows the promotional object103 of FIG. 44 in cross-section.

Covering the metal segments with different combinations of permeable andimpervious barriers allows the programming of the order and rate ofappearance and disappearance of the revealed information. Promotionalobject 103 is constructed as previously described, except that some ofthe uncovered parts 102 of the metal layer 105 are covered with one ormore light transmissive permeable barrier layers 109 b (in the presentexample, also shown as the image in the central segment in FIG. 44).

Other uncoated aluminum segments 102 were printed with impervious layers109 a and 109 c (in the present example, also shown as the image in theleft segment and the entire right segment in FIG. 44). These printedlayers 109 a-c atop the metal layer 105 alter the etching properties ofthe metal layer 105 by the etchant layer of the adhesive label 101 (alsodescribed in FIGS. 6-8 above).

In this case the image in the left segment is revealed first, as shownin FIG. 44B. This image is formed by the etching of the bare metal(aluminum in this example) layer segment 102 around an impervious layer109 a so the image does not fade at any time that is relevant to thefunction of the promotional object 103. The image of the central spot isrevealed at a second stage as it is covered by a permeable layer 109 b,around the image as shown in FIG. 44C. The image in the central segmentwill fade and disappear with time as it is printed using a permeablebarrier layer 109 b. The right aluminum segment 102 will not be etchedat any time after activation that is relevant to the function of thepromotional object 103 as shown in FIG. 44D.

If promotional object 103 is used for providing incentive(s) such as acoupon for example, the user may optionally not be most rewarded (orincentivized) by waiting for the process to end, but instead mayoptionally be most incentivized/rewarded by using the promotional objectmore rapidly.

FIG. 45 presents a cross section of a non-limiting example of apromotional object of FIG. 44.

It should be clear that the rate of the etching process of the aluminumlayers by the etchant layers are temperature dependent and so is theetching process through the permeable barrier layers. The implication ofthis temperature dependence of the process is that refrigeration relentsthe etching. In many cases, refrigeration of already activated layers to10C, 4C or −18C, depending on specific compositions, will stall theprogress of the promotional object. It is therefore possible, for someapplications and for some embodiments, to pre-activate the labels andstore them at a reduced temperature so that it is readily available forcustomers.

High Temperature Activated Promotional Object

The above non-limiting examples related to promotional objects that weresolely time dependent or time and temperature dependent. For someapplications it is desired to have a promotional object bearing a latentimage that is revealed upon crossing a given threshold temperature. Suchan implementation may optionally be performed as described in FIGS.13-14 and the accompanying text (based on melting and diffusion of amaterial) and/or as described in FIGS. 15-18 and the accompanying text(based on melting of an etchant composition and etching of a layer).

As a non-limiting example, a high temperature activated promotionalobject based on melting of an etchant composition and etching of a layermay optionally be constructed as described in FIG. 46 (top andcross-sectional views of the promotional object, shown at the right andleft, respectively). FIG. 46A presents the promotional object (100)before it is thermally activated. As shown in the top view on the right,promotional object 100 comprises a printed metal surface 150 with twobare metal segments (101) and (102). Optionally any number of bare metalsegments may be provided.

The left cross-sectional view of the promotional object 100 reveals itsstructure. A polymer layer (103) bears a very thin metal layer (forexample, aluminum) (104) on its bottom surface and printing and/orgraphics on its other (outer) side (not shown; shown as printed metalsurface 150 in the right view). The metal layer 104 is layered (asdescribed herein, optionally printed, covered, coated etc) with animpervious barrier (105) except around the portions/shapes (106) to berevealed in each metallic segment (101) and (102) at a later stage.

Metal layer 104 is in contact with an etching layer (107) that hosts twoinactivated solid etchants (109) and (110), each characterized by adifferent activation temperature. Non limiting examples of etchingcompositions contain phosphoric and/or phosphorus acid, an organicmaterial characterized by having its melting point at the desiredactivation temperature and possibly a colorant, such as for example aCongo red dye. Such an organic material may be for example myristic acidfor segments to be activated around 55 C and undecylic acid for segmentsto be activated around 29 C.

A porous and absorbing material (108) optionally separates the solidetchants (109) and (110) from the metal layer (104) at the areas thatare not protected by the impervious barrier (105). A preferably opaquelayer (111) seals the lower side of etching layer 107 (that is, the sidenot contacting metal layer 104). Optionally, adhesive (112) and liner(113) are placed under the opaque layer (111), rendering the promotionalobject 100 as a sticky label.

In this non-limiting example, preferably as long as the promotionalobject 100 is maintained below the melting temperature of the etchantcomposition having the lowest melting temperature, the promotionalobject 100 is stable with time and does not reveal any of its latentinformation. Thus, this non-limiting example represents a temperatureonly activated promotional object (optionally such objects may beconstructed to be activated by low temperatures, for exampletemperatures below freezing).

FIG. 46B describes the process of activation of the first segment (101).Upon reaching the melting temperature of the lowest melting etchantcomposition (in this example etching composition (109)), the etchingcomposition (109) liquefies (melts), absorbs into the porous material(108) and comes in contact with the metal layer (104) in parts it is notcovered by the impervious barrier layer (105). In this non-limitingexample, the metal layer 104 is aluminum. The metal layer 104 is etched,revealing the color of the etchant composition (109) and/or the color ofthe absorbing material (108) that is soaked with the etchant composition(109). This results with the appearance of a sign of a soft-drink aftersegment 101 is etched, signaling that the holder of the promotionalobject 100 won a free soft drink. As the second etchant composition(110) has a higher melting temperature (say 55 C) the metallic segment(102) does not reveal yet its latent information.

FIG. 46C describes the process of activation of the second segment(102). Upon reaching the melting temperature of the highest meltingetchant composition (in this example composition 110), the etchingcomposition (110) liquefies, absorbs into the porous material (108) andcomes in contact with the metal layer (104) in the part not covered bythe impervious barrier layer (105). The metal layer 104 is etched,revealing the color of the etchant composition (110) and/or the color ofthe absorbing material (108) that is soaked with the etchant composition(110). The etching of segment 102 results in the appearance of a symbolindicating a full meal, indicating that the holder of the promotionalobject 100 won a free meal. As the first etchant composition (109) has alower melting temperature (say 29 C) the metallic segment (101) revealedits latent information at a lower temperature and the holder of thepromotional object 100 receives both a soft drink and a meal.

As a non-limiting example, a high temperature activated promotionalobject may optionally be constructed based on melting of a compositionand diffusion, as described in FIG. 47 (top and cross section views areshown).

FIG. 47A presents the promotional object (100) before it is thermallyactivated. The various components are as described in FIG. 46, exceptthat promotional object 100 lacks metal layer 104. Instead, preferably asubstantially optically transparent polymer layer (104 a) features atleast two segments 101 a and 101 b that are nonprinted, shown asnonprinted segments 106. The remainder of polymer layer 104 a ispreferably printed, for example with colors, text, images and/orgraphics, shown as printed layer 103 a. Optionally a further printedlayer 105 a may be present below polymer layer 104 a.

Printed layer 105 a is in contact with a layer (107) that hosts twoinactivated solid colorants (109) and (110), each characterized by adifferent activation temperature. Non limiting examples of solidcolorants compositions contain an organic material characterized byhaving its melting point at the desired activation temperature andpossibly a colorant, such as for example erythrosine B. Said organicmaterial may be for example an organic acid, an organic alcohol, anorganic amine, an organic amide, an organic ester, a hydrocarbon andalike. For example, for segments to be activated around 40 C one can useheneicosane, which is a linear hydrocarbon; and for segments to beactivated around 49 C one can use hexadecanol. A porous and absorbingmaterial (108) preferably separates the solid colorants (109) and (110)from the polymer layer (104 a), at least under the areas that are notobscured by the printed layers (103 a) and/or (105 a) within thesegments (101 a) and (102 a).

The shape of the latent image may optionally be formed by destroying theabsorbing ability of layer (108) at places where the colorant should notbe absorbed, thus forming the desired shape. This may be done, forexample by selective absorption of a material at specific parts of layer108, thereby eliminating the ability of these specific parts to furtherabsorb material. A preferably opaque layer (111) seals layer 107 on theside facing away from layer 105 a. Optionally, adhesive (112) and liner(113) are placed under the opaque layer (111), rendering the promotionalobject 100 as a sticky label.

As long as the promotional object 100 is maintained below the meltingtemperature of the lowest colorant composition, the promotional object100 is stable with time and does not reveal any of its latentinformation. FIG. 47B describes the process of activation of the firstsegment (101 a). Upon reaching the melting temperature of the lowestmelting colorant composition (say 40 C, in this example the composition(109)), the composition (109) liquefies and absorbs into the absorbingparts of the porous material (108), revealing the first latentinformation such as a shape, symbol or image (in this case, asoft-drink) in segment (101 a), signaling that the holder of thepromotional object won a free soft-drink. As the second etchantcomposition (110) has a higher melting temperature (say 49 C), segment(102 a) does not reveal yet its latent information.

FIG. 47C describes the process of activation of the second segment (102a). Upon reaching the melting temperature of the highest melting etchantcomposition (say 49 C, in this example the melting temperature ofcomposition (110)), the colorant composition (110) liquefies and absorbsinto the absorbing parts of the porous material (108). This processreveals the color of the colorant composition (110) and/or the color ofthe absorbing material (108) that is soaked with the etchant composition(110). This results in the appearance of a sign of a full meal,signaling that the holder of the promotional object won a free meal. Asthe second etchant composition (110) has a higher melting temperature,segment (102 a) revealed its latent information at a higher temperature;when this higher temperature is reached, the holder of the promotionalobject 100 receives both a soft drink and a meal.

As can be appreciated, the same general embodiments outlined in FIGS. 46and 47 may be applied, with possible minor alterations, to construct alow-temperature activated promotional object based on melting of anetchant composition and etching of a layer, as well as for constructinga low-temperature activated promotional object based on melting of acomposition and diffusion. The adaptation to activation upon loweringthe temperature is achieved by, for example replacing the abovementionedetchant composition with an inverse freezing composition, such as theones described above, and adding a small amount of an etching base, suchas hydroxide salts and alike. Alternatively, this may be achieved byreplacing the abovementioned solid colorant composition by an inversefreezing composition that optionally contains a dye.

Example 2—Prize Object

According to at least some embodiments, there is provided a prizeobject, which is a time and/or temperature sensitive device having adisplay that features a prize that is won. The prize may optionally be alottery prize or the like. Optionally, the prize is only indicated asbeing won on certain prize objects, while other objects may optionallyfeature a display indicating a consolation prize or no prize. Thedisplay may optionally feature the prize in a single appearance after aset time or with a multi stage appearance, in which the display changesa plurality of times to feature the prize(s).

The prize object may optionally be implemented as described in Example1.

Example 3—Entertainment Object

According to at least some embodiments, there is provided anentertainment object, which is a time and/or temperature sensitivedevice having a display that features a story in parts or a greetingcard that reveals some type of visual indication over time. Such a storyand/or visual indication may be described as information. Thisinformation can be preprinted or variable; if the latter, optionally theinformation is controlled by the user.

The entertainment object may optionally be implemented as described inExample 1. Non-limiting examples are shown in FIG. 48 as a greetingcard. FIGS. 48A and 48B present a non-limiting example of a greetingcard with latent information that is revealed only after some time afteractivation. For example, the greeting card may be made of a fullyprinted simple card with a place to add personal words and/or asignature. This part and/or any other part of the greeting card is thencovered with a label (100) that is adhered above the part that is to beconcealed. The label (100) is composed of a transparent polymer filmthat is coated with a thin metal layer, such as an aluminum layer, andan adhesive underneath the film. The label (100) is then covered by anactivation label that is composed of a substantially transparent filmbearing an adhesive layer that contains an etchant capable of etchingthe metal layer to which it is attached. After a pre-settime/time-temperature the aluminum layer of label (100) is etched andwhat is concealed underneath is revealed, as shown in FIG. 48B.

As another non-limiting example of an entertainment object, the objectmay optionally take the form of a multiple choice story. For example, astory is printed with multiple choices; the selected option for theprogression of the story is revealed by the reader.

The book may be produced using any of the technologies described above,depending on the desired effects. The present example makes use of thetechnology outlined in FIG. 35. FIG. 49 shows a short story based on thestory “The Fox and The Crow”. FIGS. 49A and 49B depict the first twopages of the story. At the end of page two there exist two possiblepathways to the enrollment of the story. A positive answer to thequestion in page two leads to placing an etchant label atop page 3, FIG.49C. The etchant label etches the aluminum layer concealing the secondpart of the story according to the chosen scenario, FIG. 49D. The thirdpart of the story is revealed at a later stage, FIG. 49E. Alternatively,a negative answer to the question in page two directs the user to placean etchant label atop page 4, FIG. 49F. The etchant label etches thealuminum layer concealing the second part of the story according to thechosen scenario, FIG. 49G.

Example 4—Time Limited Object

According to at least some embodiments, optionally any of the aboveembodiments may be combined with a time limitation, such that after acertain amount of time has elapsed, the promotion, prize orentertainment display ceases to display the visual indication. Forexample, for an incentive such as a store coupon, the user would need tobring the coupon to the store while the visual indication was stillbeing displayed, thereby incentivizing the user to go to the store morequickly. This could be implemented as described for example with regardto FIGS. 40 and 41.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

1. A time-temperature indicator comprising a multi-layer system having ametal layer on a polymeric substrate, an etchant layer comprising anetchant that etches the metal layer when in contact therewith, theetchant layer being configured to be disposing on the side of the metallayer opposite the substrate, and a light-diffusive layer being disposedatop the etchant layer opposite the metal layer.
 2. The time-temperatureindicator according to claim 1, wherein the etchant layer is disposed onthe side of the metal layer opposite the substrate.
 3. Thetime-temperature indicator according to claim 1, wherein the polymericsubstrate is colored by at least one color.
 4. The time-temperatureindicator according to claim 3, wherein said color is a dark color. 5.The time-temperature indicator according to claim 3, wherein the coloris black.
 6. The time-temperature indicator according to claim 1,wherein the polymeric layer has a first face and a second, oppositeface, the metal layer being disposed over the first face of thepolymeric substrate and the second face being printed with signals,graphics and/or pictograms.
 7. The time-temperature indicator accordingto claim 1, wherein the polymeric layer has a first face and a second,opposite face, the metal layer being disposed over the first face of thepolymeric substrate and the second face is printed with one or morecolors on its entire surface.
 8. The time-temperature indicatoraccording to claim 1, wherein said light-diffusive layer has a hazevalue in the range of 25-60%.
 9. The time-temperature indicatoraccording to claim 1, wherein said polymeric substrate is a coloredsubstrate, having a CIE-Lab color value lower than that of the observedcolor of a freshly activated time-temperature indicator.